Method for forming pattern, thin film transistor, display device, method for manufacturing thereof, and television apparatus

ABSTRACT

To provide a display device which can be manufactured with higher efficiency in the use of material through a simplified manufacturing process, and a method for manufacturing the display device. Another object is to provide a technique by which patterns of a wiring the like which constitutes the display device can be formed to a desired shape with good control. In a method for forming a pattern according to the present invention, a mask is formed over a light-transmitting substrate; a first region including a photocatalyst is formed over the substrate and the mask; the photocatalyst is irradiated with light through the substrate to modify a part of the first region; a second region is formed; and a composition containing a pattern forming material is discharged to the second region, thus, a pattern is formed. The mask does not transmit light.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for forming a pattern, a thinfilm transistor and a manufacturing method thereof, a display device anda manufacturing method thereof, and a television apparatus using thesame.

2. Description of the Related Art

A thin film transistor (hereinafter, referred to as a “TFT”) and anelectronic circuit using the thin film transistor are manufactured bystacking various types of thin films of such as a semiconductor, aninsulator, a conductor over a substrate and then, appropriately forminga predetermined pattern by photolithography. The photolithography is atechnique of transferring a pattern of a circuit or the like formed witha material which does not transmit light over a transparent flatsurface, referred to as a photomask, onto an objective substrate byutilizing light. The technique has been widely used in the manufacturingprocesses of a semiconductor integrated circuit and the like.

In the manufacturing process employing a conventional photolithographytechnique, a multi-stage process including light exposure, development,baking, peeling, and the like are required only for treating a maskpattern which is formed of a photosensitive organic resin materialreferred to as a photoresist. Therefore, as the number of thephotolithography steps is increased, the manufacturing cost isinevitably increased. In order to improve such problems as describedabove, it has been tried to manufacture a TFT by reducing the number ofthe photolithography steps (for example, Reference 1: Japanese PatentLaid-Open No. H11-251259).

However, in the technique disclosed in Reference 1, only some of theplural photolithography steps in a TFT manufacturing process arereplaced by printing method, and no contribution is made to a drasticreduction in the number of steps. Further, a light exposure apparatus tobe used for transferring a mask pattern in photolithography transfers apattern of under several micrometers to one micrometer or less byequivalent projection light exposure or reduction projection lightexposure. It is theoretically difficult, from a technical standpoint, toexpose a large substrate which is more than one meter on a side to lightall at once using the light exposure apparatus.

SUMMARY OF THE INVENTION

It is an object of the present invention to reduce the number ofphotolithography steps in the manufacturing process of a TFT, anelectronic circuit using the TFT, and a display device formed using theTFT, and to simplify the manufacturing process. It is a further objectof the present invention to provide a technique by the TFT, theelectronic circuit, and the display device can be manufactured even overa large substrate with a side of more than one meter with higher yieldat lower cost.

It is another object of the present invention to provide a technique bywhich wiring patterns and the like constituting a display device can beformed in desired shapes with good control.

According to the present invention, an objective surface is modified byenergy due to photoactivation of a substance with photocatalyticfunction (hereinafter also referred to as a photocatalyst). The objectis formed over a light-transmitting material, and the photocatalyst isirradiated with light through the light-transmitting material from thelight-transmitting material side. On this occasion, an unirradiatedregion is provided by forming a mask between the light-transmittingmaterial and the object; thus, a region to be modified can be accuratelycontrolled. Then, a pattern forming material is adhered on the modifiedsurface by a discharge method (including an ejection method or thelike), or the like to form a pattern. Efficiency of the treatmentutilizing light can be enhanced by light-absorption of the photocatalystand by energy radiation.

A display device according to the present invention includes a lightemitting display device including an a TFT connected to a light emittingelement in which an organic material or a medium including a mixture ofan organic matter and an inorganic matter producing luminescencereferred to as electroluminescence (hereinafter also referred to as“EL”) is sandwiched between electrodes; a liquid crystal display devicein which a liquid crystal element having a liquid crystal material isused as a display element.

A method for forming a pattern according to the present inventionincludes the steps of: forming a mask over a light-transmittingsubstrate; forming a first region including a photocatalyst over thesubstrate and the mask; irradiating the photocatalyst with light throughthe substrate to modify a part of the first region which is to be asecond region; and discharging a composition containing a patternforming material to the second region to form a pattern, wherein themask does not transmit the light.

A method for forming a pattern according to the present inventionincludes the steps of: forming a mask over a light-transmittingsubstrate; forming a first region including a photocatalyst over thesubstrate and the mask; forming a material containing a fluorocarbonchain over the photocatalyst; irradiating the photocatalyst and thematerial containing the fluorocarbon chain with light through thesubstrate to modify a part of a surface of the material containing thefluorocarbon chain which is to be a second region; and discharging acomposition containing a pattern forming material to the second regionto form a pattern, wherein the mask does not transmit the light.

A method for manufacturing a thin film transistor according to thepresent invention, includes the steps of: forming a first conductivelayer over a light-transmitting substrate; forming an insulating layerover the substrate and the first conductive layer; forming a firstregion including a photocatalyst over the insulating layer; irradiatingthe photocatalyst with light through the substrate to modify a part ofthe first region which is to be a second region; and discharging acomposition containing a conductive material to the second region toform a second conductive layer, wherein the first conductive layer doesnot transmit light.

A method for manufacturing a thin film transistor according to thepresent invention, includes the steps of: forming a first conductivelayer over a light-transmitting substrate; forming an insulating layerover the substrate and the first conductive layer; forming a firstregion including a photocatalyst over the insulating layer; forming amaterial containing a fluorocarbon chain over the photocatalyst;irradiating the photocatalyst and the material containing thefluorocarbon chain with light through the substrate to modify a part ofa surface of the material containing the fluorocarbon chain which is tobe a second region; and discharging a composition containing aconductive material to the second region to form a second conductivelayer, wherein the first conductive layer does not transmit light.

According to the above structure, a display device can be manufacturedusing the first conductive layer as a gate electrode layer, and thesecond conductive layer as a source/drain electrode layer. Further, asurface of the substance can be modified so that the wettability withthe composition of the second region is higher than the first region.Still further, according to the above structure, titanium oxide having aphotocatalytic properties can be used as the photocatalyst.

A thin film transistor according to the present invention includes: afirst conductive layer provided over a light-transmitting substrate; aninsulating layer over the substrate and the first conductive layer; aphotocatalyst provided over the insulating layer; a material containinga fluorocarbon chain over the photocatalyst; a first region and a secondregion in a surface of the material containing the fluorocarbon chain;and a second conductive layer over the second region, wherein density ofthe fluorocarbon chain contained in the first region is higher thandensity of the fluorocarbon chain contained in the second region.

A thin film transistor according to the present invention includes: afirst conductive layer provided over a light-transmitting substrate; aninsulating layer over the substrate and the first conductive layer; aphotocatalyst provided over the insulating layer; a material containinga fluorocarbon chain over the photocatalyst; a first region and a secondregion are in a surface of the material containing the fluorocarbonchain; a second conductive layer provided over the second region; and asemiconductor layer formed over the material containing the fluorocarbonchain and the second electrode layer, wherein density of thefluorocarbon chain contained in the first region is higher than densityof the fluorocarbon chain contained in the second region.

A display device according to the present invention includes: a gateelectrode layer provided over a light-transmitting substrate; aninsulating layer over the substrate and the gate electrode layer; aphotocatalyst provided over the insulating layer; a material containinga fluorocarbon chain over the photocatalyst; a first region and a secondregion in a surface of the material containing the fluorocarbon chain;and a source/drain electrode layer over the second region, whereindensity of the fluorocarbon chain contained in the first region ishigher than density of the fluorocarbon chain contained in the secondregion.

A display device according to the present invention includes: a gateelectrode layer provided over a light-transmitting substrate; aninsulating layer over the substrate and the gate electrode layer; aphotocatalyst provided over the insulating layer; a material containinga fluorocarbon chain over the photocatalyst; a first region and a secondregion in a surface of the material containing the fluorocarbon chain; asource/drain electrode layer over the second region; and a semiconductorlayer formed over the material containing the fluorocarbon chain and thesource/drain electrode layer, wherein density of the fluorocarbon chaincontained in the first region is higher than density of the fluorocarbonchain contained in the second region.

A television apparatus according to the present invention includes adisplay screen constituted by a display device. The display devicecomprises: a gate electrode layer provided over a light-transmittingsubstrate; an insulating layer over the substrate and the gate electrodelayer; a photocatalyst provided over the insulating layer; a materialcontaining a fluorocarbon chain over the photocatalyst, and a firstregion and a second region in a surface of the material containing thefluorocarbon chain; and a source/drain electrode layer over the secondregion, wherein density of the fluorocarbon chain contained in the firstregion is higher than density of the fluorocarbon chain contained in thesecond region.

A television apparatus includes a display screen constituted by adisplay device. The display device includes a gate electrode layerprovided over a light-transmitting substrate; an insulating layer overthe substrate and the gate electrode layer; a photocatalyst providedover the insulating layer; a material containing a fluorocarbon chainover the photocatalyst, a first region and a second region in a surfaceof the material containing the fluorocarbon chain, a source/drainelectrode layer over the second region; and a semiconductor layer formedover the material containing the fluorocarbon chain and the source/drainelectrode layer, wherein density of the fluorocarbon chain contained inthe first region is higher than density of the fluorocarbon chaincontained in the second region.

According to the present invention, a desirable pattern can be formedwith good control. Further, the material loss and costs can be reduced.Hence, a high-performance and highly reliable display device can bemanufactured with high yield.

BRIEF DESCRIPTION OF THE DRAWING

FIGS. 1A to 1D are views describing the present invention;

FIGS. 2A and 2B are views describing of the present invention;

FIGS. 3A to 3C are views describing a method for manufacturing a displaydevice according to the present invention;

FIGS. 4A to 4C are views describing a method for manufacturing a displaydevice according to the present invention;

FIGS. 5A to 5C are views describing a method for manufacturing a displaydevice according to the present invention;

FIGS. 6A to 6C are views describing a method for manufacturing a displaydevice according to the present invention;

FIGS. 7A to 7C are views describing a method for manufacturing a displaydevice according to the present invention;

FIGS. 8A to 8C are views describing a method for manufacturing a displaydevice according to the present invention;

FIGS. 9A and 9B are views describing a method for manufacturing adisplay device according to the present invention;

FIGS. 10A to 10C are views describing a method for manufacturing adisplay device according to the present invention;

FIGS. 11A and 11B are views describing a method for manufacturing adisplay device according to the present invention;

FIGS. 12A to 12C are cross-sectional views of a display device accordingto the present invention;

FIG. 13 is a cross-sectional view describing a structural example of aliquid crystal display module according to the present invention;

FIGS. 14A to 14C are top views of a display device according to thepresent invention;

FIGS. 15A and 15B are top views of a display device according to thepresent invention;

FIG. 16 is a view describing a method for manufacturing a display deviceaccording to the present invention;

FIGS. 17A to 17F are circuit diagrams describing a structure of a pixelwhich is applicable to an EL display panel according to the presentinvention;

FIGS. 18A and 18B are views describing a display panel according to thepresent invention;

FIG. 19 is a cross-sectional view describing a structure example of anEL display module according to the present invention;

FIGS. 20A and 20B are figures showing electronic devices to which thepresent invention is applied;

FIGS. 21A to 21D are figures showing electronic devices to which thepresent invention is applied;

FIG. 22 is a cross-sectional view describing a structure example of anEL display module according to the present invention;

FIG. 23 is an equivalent circuit diagram of an EL display panelaccording to the present invention;

FIG. 24 is a top view describing an EL display module according to thepresent invention;

FIG. 25 is a view describing a circuit structure of a scan line drivercircuit in an EL display panel according to the present invention;

FIG. 26 is a diagram describing a circuit structure in a scan linedriver circuit in an EL display panel according to the present invention(a shift resistor circuit);

FIG. 27 is a diagram describing a circuit structure when a scan linedriver circuit is formed of a TFT in an EL display panel according tothe present invention (a buffer circuit);

FIG. 28 is a figure describing a structure of a droplet discharge systemwhich is applicable to the present invention;

FIG. 29 is a figure describing a droplet discharge injection methodwhich is applicable to the present invention;

FIGS. 30A to 30D show structures of light emitting elements which can beapplied to the present invention; and

FIG. 31 is a graph showing relation between light irradiation time andcontact angle of water with a surface of an irradiated substance.

DETAILED DESCRIPTION OF THE INVENTION

Embodiment Modes and Embodiment of the present invention will bedescribed in detail with reference to the accompanying drawings.However, the present invention is not limited to the followingdescription and it is easily understood by those skilled in the art thatvarious changes and modifications are possible, unless such changes andmodifications depart from the content and the scope of the presentinvention. Therefore, the present invention is to be interpreted withoutlimitation to the description in embodiment modes and the embodimentshown below. Note that, in the structure of the present inventiondescribed hereinafter, the same reference numerals denote the same partsor parts having the same functions in different drawings and theexplanation will not be repeated.

EMBODIMENT MODE 1

An embodiment mode according to the present invention is described withreference to FIGS. 1A to 1D, 2A and 2B, and 28.

One feature of the present invention is that at least one or more ofpatterns required to manufacture a display panel, such as a wiringlayer, a conductive layer for forming an electrode, or a mask layer forforming a predetermined pattern is/are formed by a method capable ofselectively forming a pattern to manufacture a display device. In thepresent invention, a pattern denotes a conductive layer such as a gateelectrode layer, a source electrode layer, or a drain electrode layer; asemiconductor layer; a mask layer; an insulating layer; or the like,which constitutes a thin film transistor and a display device, and thepattern includes any component formed so as to have a predeterminedshape. A droplet discharge (ejection) method (including an ink-jetmethod, depending on its mode) that can form a conductive layer, aninsulating layer, or the like into a predetermined pattern byselectively discharging (ejecting) a droplet of a compound mixed for aparticular purpose is employed as the method capable of selectivelyforming a pattern. In addition, a method capable of transferring ordrawing a pattern, for example, various printing methods (a method forforming a pattern, such as screen (mimeograph) printing, offset(lithography) printing, relief printing or gravure (intaglio) printingor the like can also be employed.

In this embodiment mode, a method for forming a pattern by discharging(ejecting) a compound including a fluid pattern forming material as adroplet is used. A pattern is formed by discharging a droplet includinga pattern forming material to a pattern forming region, and thecomposition is fixed by baking, drying, and the like. According to thepresent invention, pretreatment is performed on the pattern formingregion.

One mode of a droplet discharge system used for forming a pattern isshown in FIG. 28. Each of heads 1405 and 1412 of a droplet dischargemeans 1403 is connected to a control means 1407, and is controlled by acomputer 1410, so that a preprogrammed pattern can be formed. Theformation position may be determined based on a marker 1411 that isformed over a substrate 1400, for example. Alternatively, a referencepoint can be fixed based on an edge of the substrate 1400. The referencepoint is detected by an imaging means 1404, and changed into a digitalsignal by an image processing means 1409. Then, the digital signal isrecognized by the computer 1410 to generate a control signal, and thecontrol signal is transmitted to the control means 1407. An image sensorusing a charge coupled device (CCD) and a complementary metal oxidesemiconductor (CMOS) or the like can be used for the imaging means 1404.Naturally, information about a pattern to be formed over the substrate1400 is stored in a storage medium 1408, and the control signal istransmitted to the control means 1407 based on the information, so thateach head 1405 and 1412 of the droplet discharge means 1403 can beindividually controlled. Heads 1405 and 1412 are supplied with amaterial to be discharged from material supply sources 1413 and 1414through pipes, respectively.

The head 1405 has an inside structure which has a space filled with aliquid material as shown by a dotted line 1406 and a nozzle which is adischarge opening. Although it is not shown, the head 1412 has a similarinside structure to the head 1405. The sizes of the heads 1405 and 1412are different each other, and different materials can be simultaneouslydischarged with different widths. Also, a conductive material, anorganic material, an inorganic material, and the like can be dischargedfrom one head. When a droplet is drawn over a wide area such as aninterlayer insulating film, one material is simultaneously dischargedfrom a plurality of nozzles to improve a throughput, and thus, drawingcan be performed. When a large-sized substrate is used, the heads 1405and 1412 can freely scan over the substrate in a direction indicated byan arrow in FIG. 28, and a region to be drawn can be freely set. Thus, aplurality of the same patterns can be formed over one substrate.

In a method for forming a pattern such as a conductive layer by adroplet discharge method, a pattern is formed as follows. A patternforming material which is processed into particles is discharged, andfused or welded and joined by baking to solidify the pattern formationmaterial. Accordingly, a pattern which is formed by sputtering or thelike often has a columnar structure while the pattern formed by themethod according to the present invention mostly has a polycrystallinestructure with a lot of grain boundaries.

In the present invention, the vicinity of an area to be provided with apattern is irradiated with light to modify the surface selectively asshown in FIGS. 1A to 1D. A composition containing a pattern formingmaterial is adhered to the modified surface to form the pattern. Thepattern can be formed by exposure from the back of the substrate in aself-aligned manner. Consequently, according to the present invention, athin film transistor can be formed in a self-aligned manner.

Light used for the modification includes, but not limited to, infraredlight, visible light, or ultraviolet light or a combination thereof. Forexample, light emitted from an ultraviolet lamp, a black light, ahalogen lamp, a metal halide lamp, a xenon arc lamp, a carbon arc lamp,a high pressure sodium lamp, or a high pressure mercury lamp may beused. The lamp light source may be activated for a required time, or maybe activated plural times.

Further, a laser beam may be used as the light for modification. A lasercapable of emitting ultraviolet light, visible light, or infrared lightcan be used. For example, an excimer laser of such as KrF, ArF, KrF,XeCl, or Xe, a gas laser of He, He—Cd, Ar, He—Ne, HF, a solid-statelaser using a crystal of such as YAG, GdVO₄, YVO₄, YLF, or YAlO₃ dopedwith Cr, Nd, Er, Ho, Ce, Co, Ti, or Tm, or a semiconductor laser of suchas GaN, GaAs, GaAlAs, or InGaAsP can be used. In the case of using asolid-state laser for the light, it is preferable to apply the secondharmonic, or the third harmonic of the fundamental wave. An opticalsystem including a shutter, a reflector such as a mirror, or a halfmirror, and a cylindrical lens or a convex lens may be used forcontrolling the shape and the course of the laser beam emitted from alaser oscillator.

The substrate may be moved for selective light irradiation, or light maybe moved in x-y direction for irradiation. In this case, a polygonmirror or a galvano mirror is preferably used in the optical system.

In this embodiment mode, light is irradiated from the back of thesubstrate to modify and change the wettability of the irrradiated area.Thus, areas having different wettabilities for a composition containinga pattern forming material are formed in the vicinity of the patternforming region. The wettability of the areas with the compositioncontaining the pattern forming material may have relative difference asthe difference between the wettability of the pattern forming region andthe periphery thereof where a pattern is not formed (non-pattern formingregion). The areas having different wettability have different contactangles. An area having a larger contact angle with the pattern formingmaterial is an area having lower wettability (hereinafter, also referredto as a “low-wettability region”), and an area having a smaller contactangle of with the pattern forming material is an area having highwettability (hereinafter, also referred to as a “high-wettabilityregion”). This is because when a contact angle is large, a liquidcomposition having fluidity does not spread and repelled on the surfaceof the area; therefore, the surface is not wetted; and when an contactangle is small, a composition having fluidity spreads over the surface,and the surface is wetted. Accordingly, the areas having differentwettability have different surface energy. The surface of the lowwettability region has low surface energy, and the surface of the highwettability region has high surface energy. In the present invention,the difference of contact angles between the areas having differentwettability is 30° or more, preferably, 40° or more.

In this embodiment mode, light irradiation treatment is performed toform regions having different wettability. A material is formed over apattern forming region and the periphery thereof, and treatment forselectively enhancing wettability and treatment for selectivelydecreasing wettability are performed with the use of the light. In thisembodiment mode, a material having low wettability is formed over theperiphery of the pattern forming region, and light capable ofdecomposing the material having low wettability is radiated to decomposeand remove the substance having low wettability in a treatment region.Thus, wettability of the treatment region is enhanced, and ahigh-wettability region is formed. A material having low wettability maybe a substance containing a material having an effect of decreasing thewettability. The material which decreases wettability is decomposed anddestroyed by laser irradiation treatment to neutralize the effect ofdecreasing wettability. It is necessary to use light having a wavelengthwhich is absorbed by the material having low wettability. Consequently,the concentration of the low wettability substance contained in the lowwettability region (For example, the concentration or the amount of thefluorocarbon chain which has an effect of reducing wettability) becomeslower than that in the high wettability region. A material having lowwettability may be a material containing a material having an effect ofreducing wettability. The material which reduces wettability isdecomposed and destroyed by laser irradiation treatment to neutralizethe effect of reducing wettability.

According to the present invention, an object is irradiated with lightthrough a material (substrate) provided with the object to form theareas having different wettability with good control. In this embodimentmode, a mask is formed in advance over a light-transmitting substrate,and then a low wettability material is formed thereover. The materialwhich reduces wettability in the material having low wettability of thearea other than the mask region is decomposed by light irradiation fromthe light-transmitting substrate side. The material having lowwettability which is formed over the mask region is not irradiated withlight; thus, the areas having different wettabilities are formed withgood control. The light is required to have a wavelength by which thematerial having low wettability is decomposed and removed. However,light with a wavelength of 200 nm or less which has large energy, suchas ultraviolet light, is required depending on the material; therefore,the range of choice is narrowed. Further, in the case of the wavelengthwhich the light-transmitting material in the substrate absorbs, thelight is absorbed in the light-transmitting substrate, and the object isnot irradiated with light; accordingly, the surface can not be modified.Additionally, it is also required to irradiate plural times to performsufficient treatment; therefore, the cost or time necessary for theapparatus or the process is increased, so that the production efficiencyis reduced.

Accordingly, in the present invention, a photocatalyst is formed incontact with the object, in order to improve the efficiency of lightirradiation. The photocatalyst absorbs light and id activated. Theactivating energy acts on the substance around and consequently modifiesthe substance by changing the properties thereof. The photocatalystimproves the efficiency of modifying according to the present invention;thus, the range of options for the light wavelength is increased.Consequently, the wavelength that is hardly absorbed by the substance tobe provided with the object can be selected, and light irradiation forcontrollable surface modification treatment can be carried out. Further,the efficiency of light irradiation can be improved, so that thetreatment can be done sufficiently even though the light itself has lowenergy. As a result, the apparatuses and steps are simplified, thus,costs and time are reduced, and the production efficiency can beimproved.

In this embodiment mode, an example of forming a wiring pattern withgood control will be shown. First, a mask 70 is formed over alight-transmitting substrate 50 (FIG. 1A). Since the mask 70 is made toserve as a mask for blocking light, a material which hardly transmitlight is required to be used. In this embodiment mode, an insulatingmaterial is used for the mask 70, and a conductive material is used fora pattern 75 a and a pattern 75 b which are formed over the mask 70. Inthis case, the mask 70 serves as an insulator which electricallyinsulates the wirings constituted by the pattern 75 a and the pattern 75b. In the case of using a conductive material for the mask 70, thepattern 75 a, and the pattern 75 b, if an insulating layer is formedbetween the mask 70, and the pattern 75 a and the pattern 75 b, and theinsulating layer is pretreated according to the present invention, thewiring may be formed to have a layered structure.

Next, a photocatalyst 80 is formed. Titanium oxide (TiO_(X)), strontiumtitanate (SrTiO₃), cadmium selenide (CdSe), potassium tantalate (KTaO₃),cadmium sulfide (CdS), zirconia (ZrO₂), niobium oxide (Nb₂O₅), zincoxide (ZnO), iron oxide (Fe₂O₃), tungsten oxide (WO₃), and the like arepreferable for the photocatalyst. The photocatalyst can be irradiatedwith light in the ultraviolet range (wavelength of 400 nm or less,preferably, 380 nm or less) for activating the photocatalytic.

The photocatalyst can be formed by dip coating using sol-gel process,spin coating, a droplet discharge method, ion plating, an ion beamtechnique, CVD, sputtering, RF magnetron sputtering, plasma spraying, oranodic oxidation. In addition, the substance need not have continuity asa film, depending on its formation method. In the case of aphotocatalyst made of an oxide semiconductor containing a plurality ofmetals, the photocatalyst can be formed by mixing salts containing theconstituent elements and melting them. In the case of forming thephotocatalyst by a coating method such as dip coating or spin coating,the photocatalyst may be baked or dried to remove the solvent asnecessary. Specifically, it may be heated at a predetermined temperature(for example, 300° C. or more), preferably, in an atmosphere containingoxygen.

Through the heat treatment, the photocatalyst can acquire apredetermined crystal structure. For example, it has an anatasestructure or a rutile-anatase mixed structure. The anatase structure ispreferentially formed in the low temperature phase. Thus, thephotocatalyst may also be heated when it does not have a predeterminedcrystal structure. In addition, in the case of forming the photocatalystby a coating method, it can be formed plural times to obtain apredetermined film thickness.

Further, a transition metal (such as Pd, Pt, Cr, Ni, V, Mn, Fe, Ce, Mo,or W) can be doped into the photocatalyst, so that the photocatalyticactivity is enhanced or the photocatalyst can be activated by light inthe visible range (wavelength of 400 nm to 800 nm). This is because atransition metal can form a new level within a forbidden band of anactive photocatalyst having a wide band gap and can expand the lightabsorption range to the visible range. For example, an acceptor such asCr or Ni, a donor such as V or Mn, an amphoteric impurity such as Fe, orother types such as Ce, Mo, W, or the like can be doped. Thus, thewavelength of light can be determined depending on the photocatalyst.Therefore, light irradiation in the present invention denotesirradiation with light having such a wavelength that activates thephotocatalyst.

When the photocatalyst is heated and reduced in vacuum or under hydrogenflow, an oxygen deficiency is caused in the crystal. Even when thetransition element is not doped, an oxygen deficiency plays a similarrole to an electron donor in this manner. In particular, in the case offorming the photocatalyst by sol-gel process, the photocatalyst need notbe reduced since an oxygen deficiency exists from the beginning. Inaddition, an oxygen deficiency can be caused by doping a gas of N₂ orthe like.

In this embodiment mode, a titanium oxide layer is formed as aphotocatalyst. The titanium oxide layer is formed by spin coating withTiCl₃ solution, and baking in an oxygen atmosphere.

In this embodiment mode, a layer 81 comprising a substance having lowwettability is formed over the photocatalyst 80. In this embodimentmode, the substance having low wettability is mixed into a solvent orthe like; thus, the substance in liquid form is selectively dischargedby a droplet discharge method. However, the method for forming thesubstance having low wettability is not limited to this embodiment modesince the substance may be attached to the pattern formation region andthe periphery thereof. For example, the substance having low wettabilitycan be formed by sol-gel dip coating, spin coating, a droplet dischargemethod, ion plating, an ion beam method, CVD, sputtering, RF magnetronsputtering, or plasma spraying. In the case of using a coating methodsuch as dip coating or spin coating, and when a solvent should beremoved, baking or drying may be performed. In the case of using amethod of forming a pattern directly over the pattern forming region,such as a droplet discharge method, the cost can be curtailed since thematerials can be used efficiently.

A composition containing a substance having a low wettability isdischarged as a droplet 85 from a discharge device 84 to thephotocatalyst 80 as shown in FIG. 1B, so that the layer 81 comprisingthe substance that is less low wettability substance is formed.

The photocatalyst 80 is irradiated with light 89 from a light source 86through the substrate 50 (FIG. 1C). Since the substrate hasphotocatalytic properties, it is activated by the applied light; thus,the substance having low wettability is decomposed and destroyed, sothat the wettability of the treatment area is improved. The light 89 isblocked by a mask 70, so that a portion of the substance having lowwettability over the mask 70 is not irradiated. Accordingly, a highwettability region 72 a and a high wettability region 72 b which arehighly low wettability substance are formed; thus, an area havingdifferent wettability is formed at the periphery of the patternformation region. Therefore, the non-treated area becomes relatively lowwettability substance to be a low wettability region 71 (FIG. 1D)

Afterwards, a droplet 74 containing the pattern forming material isdischarged from a nozzle of a droplet discharge system 73 to thehigh-wettability regions 72 a and 72 b which are regions on whichpatterns are to be formed. The discharged droplet 74 adheres to thehigh-wettability regions 72 a and 72 b without adhering to thelow-wettability region 71 (see FIG. 2A). Even when the pattern formingmaterial can not be discharged precisely depending on the size of thedischarge opening of the nozzle from which the droplet is discharged orthe moving ability of the discharge opening, the droplet is attachedonly to the regions to form desired patterns 75 a and 75 b by performingtreatment for enhancing wettability on the regions (see FIG. 2B). Thisis because the region on which a pattern is to be formed (the patternformation region) and the periphery thereof have different wettability;therefore, the droplet is repelled only in the low-wettability regionand remains on the region having higher wettability. In other words, thedroplet is repelled by the low-wettability region next to thehigh-wettability region; therefore, the boundary between thehigh-wettability region and the low-wettability region functions as apartition wall (a bank). Accordingly, even the composition containingthe pattern forming material having fluidity can remain on thehigh-wettability region; thus, the pattern can be formed to have adesired shape.

According to the present invention, when a fine pattern of, for example,a conductive layer, or the like is formed, a droplet does not spreadover the pattern formation region even when a discharge opening of thedroplet is somewhat large, therefore, a conductive layer can be formedonly on the pattern formation region, and faults such as short circuitwhich can be caused by forming the conductive layer in an area otherthan the pattern formation region. Additionally, film thickness of thewiring can be controlled. As in this embodiment mode, when the surfaceof the substance is modified by light irradiation from the substrateside, a large area can be treated in addition to forming a pattern;thus, production efficiency is improved. By combining a dropletdischarge method, the material loss can be avoided compared with entiresurface application formation by spin coating or the like; therefore,the cost can be reduced. According to the present invention, a patterncan be formed with good control even in the case where wirings or thelike are designed integrally and intricately due to miniaturization andthinner film formation.

In this embodiment mode, a photocatalyst and a substance having lowwettability are formed as pretreatment. They could be extremely thindepending on the formation condition, so that they may not have filmform.

Treatment for enhancing wettability is carried out to make the strengthof holding a droplet discharged over a region (also referred to as“adhesion forth” or “fixing strength”) stronger than that of theperiphery thereof, which is equivalent to enhancing the adhesion withthe droplet by modifying the region. The wettability needs only on asurface which is in contact with and holds a droplet, and the whole filmdoes not necessarily have the similar properties.

After forming the pattern, the photocatalyst and the substance whichchanges wettability formed for pretreatment after forming the patternmay be left, or an unnecessary portion may be removed. In the removal,the pattern may be used as a mask, and ashing using oxygen or the like,etching, plasma treatment, or the like may be used.

As an example of the composition of the solution for forming thelow-wettability region, a silane coupling agent expressed in a chemicalformula of R_(n)—Si—X_((4−n)) (n=1, 2, 3) is used. Here, R denotes asubstance which contains a comparatively inactive group such as an alkylgroup. Further, X includes a hydrolysable group which can be bonded bythe condensation with a hydroxyl group or absorbed water on a surfacesuch as halogen, a methoxy group, an ethoxy group, or an acetoxy group.

Using a fluorine-based silane coupling agent (fluoroalkylsilane(hereinafter referred to as FAS)) having a fluoroalkyl group for R thatis a representative example of the silane coupling agent, thewettability can be lowered. R of FAS has a structure which is expressedin (CF₃)(CF₂)_(x)(CH₂)_(y) (x: an integer from 0 to 10, y: an integerfrom 0 to 4). In the case where a plurality of R or X are bonded to Si,the R or X may all be the same or different each other.Fluoroalkylsilane such as heptadecafluorotetrahydrodecyltriethoxysilane, heptadecafluorotetrahydrodecyltrichlorosilane, tridecafluorotetrahydrooctyltrichlorosilane,trifluoropropyltrimethoxy silane are typically used.

As the solvent of a solution for forming the low-wettability region, asolvent which forms a low-wettability region such as a hydrocarbon-basedsolvent, tetrahydrofuran, dioxane ethanol, dimethyl sulfoxide, or thelike, namely, n-pentane, n-hexane, n-heptane, n-octane, n-decane,dicyclopentane, benzene, toluene, xylene, durene, indene,tetrahydronaphthalene, decahydronaphthalene, squalene, or the like canbe used.

As an example of the compound of the solvent for forming thelow-wettability region, a substance having a fluorocarbon chain(fluorine resin) can be used. As the fluorine resin,polytetrafluoroethylene (PTFE; polytetrafluoroethylene resin),perfluoroalkoxyalkane (PFA; tetrafluoroethylene perfluoroalkylvinylethercopolymer resin), perfluoroethylene propylene copolymer (PFEP;tetrafluoroethylene hexafluoropropylene copolymer resin),ethylene-tetrafluoroethylene copolymer (ETFE;tetrafluoroethylene-ethylene copolymer resin), polyvinylidene fluoride(PVDF; polyvinylidene fluoride resin), polychlorotrifluoroethylene(PCTFE; polytrifluorochloroethylene resin),ethylene-chlorotrifluoroethylene copolymer (ECTFE;polytrifluorochloroethylene-ethylene copolymer resin),polytetrafluoroethylene-perfluorodioxol copolymer (TFE/PDD),polyvinylfluoride (PVF; vinyl fluoride resin), or the like can be used.

In addition, an organic material which does not form a low-wettabilityregion (in other words, which forms a high-wettability region) may beused to form a low wettability region by performing treatment with theuse of CF₄ plasma or the like later. For example, a material in which asoluble resin such as polyvinyl alcohol (PVA) is mixed into a solvent ofsuch as H₂O can be used. In addition, PVA may be mixed with anothersoluble resin may be used. An organic material (an organic resinmaterial) (polyimide, acrylic), a material in which a skeleton is formedby the bond of silicon (Si) and oxygen (O), and which includes anorganic group containing at least hydrogen as a substituent.Alternatively, a fluoro group, an alkyl group, or aromatic hydrocarbonmay be used as the substituent. Even when a material having alow-wettability region is used, wettability can be further reduced byperforming plasma treatment or the like.

A base film may be formed to improve adhesion between the pattern andthe pattern formation region. For example, when a conductive materialcontaining silver is applied to a substrate to form a silver wiring asthe mask, a titanium oxide film may be formed over the substrate toimprove the adhesion. The titanium oxide film has good adhesion with theconductive material containing silver to be formed later, therebyenhancing reliability.

According to the present invention, a desirable pattern can be formedwith good control. Further, the material loss and costs can be reduced.Hence, a high-performance and highly reliable light emitting displaydevice can be manufactured with high yield.

EMBODIMENT MODE 2

An embodiment mode according to the present invention will be describedwith reference to FIGS. 3A to 3C, 4A to 4C, 5A to 5C, 6A to 6C, 7A to7C, 8A to 8C, 9A, 9B, 14A to 14C, 15A and 15B. More specifically, amethod for manufacturing a display device having a channel etch typethin film transistor according to the present invention will bedescribed. Each of FIGS. 3A, 4A, 5A, 6A, 7A, and 8A shows a top view ofa pixel portion in a display device, each of FIGS. 3B, 4B, 5B, 6B, 7B,and 8B shows a cross-sectional view taken along line A-C in FIGS. 3A,4A, 5A, 6A, 7A, and 8A, and each of FIGS. 3C, 4C, 5C, 6C, 7C, and 8Cshows a cross-sectional view taken along line B-D in FIGS. 3A, 4A, 5A,6A, 7A, and 8A.

FIG. 14A is a top view showing a structure of a display panel accordingto the present invention. A pixel portion 2701 in which pixels 2702 arearranged in matrix, a scan line input terminal 2703, and a signal lineinput terminal 2704 are formed over a substrate 2700 having aninsulating surface. The number of the pixels may be determined inaccordance with various standards. The number of pixels of XGA may be1024×768×3 (RGB), that of UXGA may be 1600×1200×3 (RGB), and that of afull-spec high vision may be 1920×1080×3 (RGB).

The pixels 2702 are arranged in matrix by intersecting a scan lineextended from the scan line input terminal 2703 and a signal lineextended from the signal line input terminal 2704. Each of the pixels2702 is provided with a switching element and a pixel electrodeconnected thereto. A typical example of the switching element is a TFT.The gate electrode of the TFT is connected to the scan line, and thesource or drain thereof is connected to the signal line, which enableseach pixel to be controlled independently by a signal input fromoutside.

The TFT includes a semiconductor layer, a gate insulating layer, and agate electrode layer as its main components. A wiring layer connected toa source/drain region formed in the semiconductor layer also accompanieswith the TFT. A top gate type TFT in which a semiconductor layer, a gateinsulating layer, and a gate electrode layer are arranged from thesubstrate side, a bottom gate type TFT in which a gate electrode layer,a gate insulating layer, and a semiconductor layer are arranged from thesubstrate side, and the like are known as typical structures of a TFT.Any one of the structures may be applied to the present invention.

An amorphous semiconductor (hereinafter also refereed to as a “AS”)manufactured by a vapor phase growth method or sputtering using asemiconductor material gas typified by silane or germane; apolycrystalline semiconductor that is formed by crystallizing theamorphous semiconductor by utilizing light energy or thermal energy; asemiamorphous (also referred to as microcrystalline or microcrystal)semiconductor (hereinafter also referred to as a “SAS”); or the like canbe used as a material for forming the semiconductor layer.

The SAS is a semiconductor having an intermediate structure between anamorphous structure and a crystalline structure (including a singlecrystal and a polycrystal) and having a third state which is stable interms of free energy, and includes a crystalline region havingshort-range order and lattice distortion. A crystalline region of from0.5 nm to 20 nm can be observed in at least a part of a region in thefilm. When silicon is contained as the main component, a Raman spectrumis shifted to a lower frequency side than 520 cm⁻¹. A diffraction peakof (111) or (220) to be caused by a crystal lattice of silicon isobserved in X-ray diffraction. Hydrogen or halogen of at least 1 atomic% or more is contained to terminate a dangling bond. The SAS is formedby glow discharge decomposition (plasma CVD) of a silicide gas. SiH₄ isused as a typical silicide gas. In addition, Si₂H₆, SiH₂Cl₂, SiHCl₃,SiCl₄, SiF₄, or the like can also be used as the silicide gas. Further,F₂ or GeF₄ may be mixed. This silicide gas may be diluted with H₂, or H₂and one or more rare gas elements selected from He, Ar, Kr, and Ne. Thedilution ratio ranges from 1:2 to 1:1000. The pressure rangesapproximately from 0.1 Pa to 133 Pa, and the power frequency ranges from1 MHz to 120 MHz, preferably from 13 MHz to 60 MHz. The substrateheating temperature may be 300° C. or less, and the film can also beformed at temperatures of from 100° C. to 200° C. It is desirable thatan atmospheric constituent impurity such as oxygen, nitrogen, or carbonis 1×10²⁰ atoms/cm³ or less as an impurity element in the film;specifically, an oxygen concentration is 5×10¹⁹ atoms/cm³ or less,preferably 1×10¹⁹ atoms/cm³ or less. A preferable SAS can be obtained byfurther promoting lattice distortion by adding a rare gas element suchas helium, argon, krypton or neon to enhance stability. Additionally, aSAS layer formed using a hydrogen-based gas may be stacked over a SASlayer formed using a fluorine-based gas.

FIG. 14A shows a structure of a display panel in which a signal to beinput to a scan line and a signal line is controlled by an externaldriver circuit. Alternatively, a driver IC 2751 may be mounted on asubstrate 2700 by COG (Chip on Glass) method as shown in FIG. 15A. Asanother mounting mode, TAB (Tape Automated Bonding) may be also used asshown in FIG. 15B. The driver IC may be formed over a single crystalsemiconductor substrate or may be formed with a TFT, over a glasssubstrate. In FIGS. 15A and 15B, a driver IC 2751 is connected to an FPC(Flexible Printed Circuit) 2750.

When a TFT provided in a pixel is formed of a SAS, a scan line drivercircuit 3702 may be integrally formed over a substrate 3700 as shown inFIG. 14B. In FIG. 14B, a pixel portion 3701 is controlled by an externaldriver circuit which is connected to a signal line input terminal 3704in the same manner as in FIG. 14A. When a TFT provided in a pixel isformed of a polycrystalline (microcrystalline) semiconductor, a singlecrystal semiconductor, or the like having high electron mobility, apixel portion 4701, a scan line driver circuit 4702 and a signal linedriver circuit 4704 can be integrally formed over a substrate 4700 asshown in FIG. 14C.

A glass substrate formed of barium borosilicate glass, aluminoborosilicate glass, or the like; a quartz substrate; a siliconsubstrate; a metal substrate; a stainless-steel substrate; or a plasticsubstrate which can withstand the process temperature of themanufacturing process is used for a light-transmitting substrate 100(FIGS. 3B and 3C). The surface of the light-transmitting substrate 100may be polished by CMP or the like to be planarized. In addition, aninsulating layer may be formed over the light-transmitting substrate100. The insulating layer is formed of a single layer or a laminate by aknown method such as CVD, plasma CVD, sputtering, or spin coating usingan oxide material or nitride material including silicon. The insulatinglayer is not necessarily formed; however, it has an effect of blockingcontaminants from the substrate 100. In the present invention, inmodifying the pattern forming region, a surface of the formed substanceis modified by being irradiated with light through thelight-transmitting substrate 100 by back exposure. Accordingly, thelight-transmitting substrate 100 is required to be a substance whichtransmits enough light to modify the pattern formation region.

Gate electrode layers 103 and 104 are formed over the light-transmittingsubstrate 100 (FIGS. 3A to 3C). The gate electrode layers 103 and 104can be formed by CVD, sputtering, a droplet discharge method, or thelike. The gate electrode layers 103 and 104 may be formed with anelement selected from Ta, W, Ti, Mo, Al, and Cu, an alloy material or acompound material mainly containing the element. Alternatively, asemiconductor film typified by a polycrystalline silicon film doped withan impurity element such as phosphorus, or AgPdCu alloy may be used.Either single layer structure or layered structure may be used. Forexample, a two-layer structure of a tungsten nitride (TiN) film and amolybdenum (Mo) film, or a three-layer structure in which a 50 nm thicktungsten film, a 500 nm thick alloy (Al—Si) film of aluminum andsilicon, and a 30 nm titanium nitride film are stacked in order.Further, in the case of the three-layer structure, tungsten nitride maybe used instead of the tungsten of the first conductive film, an alloy(Al—Ti) film of aluminum and titanium may be used instead of the alloy(Al—Si) film of silicon and aluminum of the second conductive film, anda titanium film may be used instead of the titanium nitride film of thethird conductive film.

In the case where the gate electrode layers 103 and 104 are required tobe patterned to a shape, patterning may be carried out by dry etching orwet etching after forming a mask. The electrode layers can be etched toa desired tapered shape by ICP (Inductively Coupled Plasma) etchingappropriately controlling the etching condition (the amount of electricpower applied to a coiled electrode, the amount of electric powerapplied to an electrode of a substrate side, the temperature of theelectrode of the substrate side, or the like). Note that achlorine-based gas typified Cl₂, BCl₃, SiCl₄, and CCl₄; a fluorine-basedgas typified by CF₄, SF₆, and NF₃; or O₂ can be appropriately used forthe etching gas.

The mask for patterning can be formed by selectively discharging thecomposition. The patterning steps can be simplified by thus forming amask selectively. A resin material such as epoxy resin, acrylic resin,phenol resin, novolac resin, melamine resin, or urethane resin is usedfor the mask. In addition, the mask may be formed by a droplet dischargemethod using an organic material such as benzocyclobutene, parylene,flare, or light-transmitting polyimide; a compound material made by thepolymerization of such as a siloxane-based polymer; a compositionmaterial containing a water-soluble homopolymer and a water-solublecopolymer; or the like. Alternatively, a commercial resist materialcontaining a photosensitizer may be used. For example, a typicalpositive type resist such as a novolac resin and a naphthoquinonediazide compound that is a photosensitizer, or a negative type resistsuch as a base resin and diphenylsilanediol and an acid generator may beused. In using any material, the surface tension and the viscosity areappropriately controlled by diluting the concentration of a solvent oradding a surfactant or the like.

In this embodiment mode, the gate electrode layer 103 and the gateelectrode layer 104 are formed by a droplet discharge means. The dropletdischarge means is a general term for one having a means of discharginga droplet such as a nozzle having a discharge opening of a compositionor a head equipped with one or plural nozzles. The diameter of thenozzle included in the droplet discharge means is set in the range offrom 0.02 μm to 100 μm (preferably, 30 μm or less), and the amount ofthe composition to be discharged from the nozzle is set in the range offrom 0.001 pl to 100 pl (preferably, 0.1 pl to 40 pl, more preferably,10 pl or less). The amount of the composition to be discharged increasesin proportion to the size of the diameter of the nozzle. Further, it ispreferable that the distance between an object to be processed and thedischarge opening of the nozzle is as short as possible in order to dropthe droplet on a desired position. Favorably, the distance is setapproximately in about the range from 0.1 mm to 3 mm (more preferably, 1mm or less).

As for the composition to be discharged from the discharge opening, aconductive material dissolved or dispersed in a solvent is used. Theconductive material is fine particles or dispersed nanoparticles ofmetal such as Ag, Au, Cu, Ni, Pt, Pd, Ir, Rh, W, or Al, sulfide of metalsuch as Cd or Zn, oxide of Fe, Ti, Si, Ge, Zr, Ba, or the like, orsilver halide. The conductive material may be indium tin oxide (ITO),ITSO formed of indium tin oxide and silicon oxide, organic indium ororganotin, zinc oxide, titanium nitride, or the like, which is used as atransparent conductive film. However, as for compositions to bedischarged from the discharge opening, it is preferable to use any oneof the materials of gold, silver, and copper, which is dissolved ordispersed in a solvent, taking a specific resistance value intoconsideration. It is more preferable to use silver or copper having alow resistance value. When silver or copper is used, a barrier film maybe additionally provided as a countermeasure against impurities. Asilicon nitride film or nickel boron (NiB) can be used for the barrierfilm.

In addition, a particle in which a conductive material is coated withanother conductive material to form a plurality of layers may be used.For example, a three-layer structure particle in which copper is coatedwith nickel boron (NiB), which is further coated with silver may beused. As for the solvent, esters such as butyl acetate and ethylacetate; alcohols such as isopropyl alcohol and ethyl alcohol; organicsolvents such as methyl ethyl ketone and acetone; or the like may beused. The viscosity of the composition is preferably 20 mPa·s or less.This prevents the composition from drying, or the composition issmoothly discharged from the discharge opening. The surface tension ofthe composition is preferably 40 mN/m or less. However, the viscosity ofthe composition and the like may be appropriately controlled inaccordance with a solvent to be used and use application. For example,the viscosity of a composition in which ITO, organic indium, ororganotin is dissolved or dispersed in the solvent may be set from 5mPa·s to 20 mPa·s, the viscosity of a composition in which silver isdissolved or dispersed in the solvent may be set from 5 mPa·s to 20mPa·s, and the viscosity of a composition in which gold is dissolved ordispersed in a solvent may be set from 5 mPa·s to 20 mPa·s.

The conductive layer may be formed by stacking a plurality of conductivematerials. In addition, the conductive layer may be formed by a dropletdischarge method using silver as a conductive material; thereafter, itmay be plated with copper or the like. Plating may be performed byelectroplating or a chemical (electroless) plating method. Plating maybe performed by soaking a substrate surface into a container filled witha solution containing a plating material. The solution containing aplating material may be applied so that the solution flows over thesubstrate surface with the substrate placed obliquely (or vertically).When the plating is performed by applying a solution with the substrateplaced vertically, there is an advantage that a process apparatus can besmaller.

The diameter of a particle of the conductor is preferably as small aspossible for the purpose of preventing nozzles from being clogged andmanufacturing a fine pattern, although it depends on the diameter ofeach nozzle, a desired shape of a pattern, and the like. Preferably, thediameter of the particle of the conductive material is 0.1 μm or less.The composition is formed by a known method such as an electrolyzingmethod, an atomizing method, a wet reducing method, or the like, and theparticle size thereof is typically about from 0.01 μm to 10 μm. However,when a gas evaporation method is employed, nanoparticles protected witha dispersant are minute, about 7 nm. When the surface of each particleis covered with a coating, the nanoparticles do not aggregate in thesolvent and are uniformly dispersed in the solvent at room temperature,and behaves similarly to liquid. Accordingly, it is preferable to use acoating.

In the present invention, it is necessary that the composition hasfluidity even when it touches the object to be processed since it isprocessed to have a desired pattern shape by utilizing the difference inwettability with respect to the fluid composition between a patternforming region and the periphery thereof. However, the process ofdischarging a composition may be performed under reduced pressure iffluidity is not lost. In addition, when the process is performed underreduced pressure, an oxide film or the like is not formed over thesurface of the conductive material, which is preferable. Afterdischarging the composition, either or both steps of drying and bakingis/are performed. Each step of drying and baking is carried out by heattreatment. For example, drying is performed for three minutes at 100° C.and baking is performed for 15 minutes to 60 minutes at a temperature offrom 200° C. to 350° C., each of which has a different purpose,temperature, and period. The steps of drying and baking are performed atnormal pressure or under reduced pressure by laser light irradiation,rapid thermal annealing, heating using a heating furnace, or the like.Note that the timing of the heat treatment is not particularly limited.The substrate may be heated to favorably perform the steps of drying andbaking. The temperature of the substrate at the time depends on thematerial of the substrate or the like, but it is typically 100° C. to800° C. (preferably, from 200° C. to 350° C.). With the steps,nanoparticles are made in contact with each other and fusion and weldingare accelerated by hardening and shrinking a peripheral resin as well asevaporating the solvent in the composition or chemically removing thedispersant.

A continuous wave or pulsed gas laser or a solid-state laser may be usedfor laser light irradiation. An excimer laser, a YAG laser, and the likecan be used as the former gas laser. A laser using a crystal of YAG,YVO₄, GdVO₄, or the like which is doped with Cr, Nd, or the like can beused as the latter solid-state laser. Note that it is preferable to usea continuous wave laser in relation to the absorptance of laser light.Moreover, a so-called hybrid laser irradiation method which combinespulse and continuous wave may be used. However, it is preferable thatthe heat treatment by laser light irradiation is instantaneouslyperformed within several microseconds to several tens of seconds so asnot to damage the substrate 100, depending on heat resistance of thesubstrate 100. Rapid thermal annealing (RTA) is carried out by raisingthe temperature rapidly and heating for several microseconds to severalminutes using an infrared lamp or a halogen lamp emitting light of fromultraviolet to infrared in an inert gas atmosphere. Since the treatmentis performed instantaneously, only a thin film on a top surface can besubstantially heated and a lower layer film is not affected.Accordingly, even a substrate having low heat resistance such as aplastic substrate is not affected.

After forming the gate wiring layers 103 and 104 by discharging acomposition by a droplet discharge method, the surface thereof may beplanarized by pressing it with pressure to enhance its planarity. As apressing method, unevenness may be smoothed by making a roller-shapedobject moved over the surface, or the surface may be vertically pressedwith a flat plate-shaped object. A heat process may be performed at thetime of pressing. Alternatively, unevenness on the surface may beeliminated with an air knife by softening or melting the surface with asolvent or the like. A CMP method may be also used for polishing thesurface. This step may be applied for planarizing a surface whenunevenness is caused by a droplet discharge method.

Subsequently, a gate insulating layer 106 is formed over the gateelectrode layers 103 and 104 (see FIGS. 3A to 3C). The gate insulatinglayer 106 is required to transmit light so that a photocatalyst formedthereover is activated by light irradiation. The gate insulating layer106 may be formed of a known material such as an oxide or nitride ofsilicon, and may be a laminate or a single layer. In this embodimentmode, a laminated layer of three layers of a silicon nitride film, asilicon oxide film, and a silicon nitride film is used. Alternatively, asingle layer of them or of a silicon oxynitride film, or a laminatedlayer of two layers may be used. A silicon nitride film having fine filmquality may be preferably used. In the case of using silver, copper, orthe like for the conductive layer formed by a droplet discharge method,in forming a silicon nitride film or a NiB film thereover as a barrierfilm, the silicon nitride film or the NiB film is effective inpreventing impurities from diffusing and in planarizing the surface.Note that a rare gas element such as argon is preferably included in areactive gas and is preferably mixed into the insulating film to beformed in order to form a fine insulating film with little gate leakcurrent at a low film-formation temperature.

As pretreatment for forming a source/drain electrode layer with goodcontrol, the periphery of a pattern forming region is modified to havedifferent wettability from the region therearound. In this embodimentmode, a photocatalyst is formed and a substance having low wettabilityis formed thereon. The wettability is selectively changed by irradiationtreatment to form a high-wettability region and a low-wettabilityregion. The difference in wettability can be confirmed by the contactangle that is 30° or more, preferably, 40° or more. In the presentinvention, a photocatalyst which is activated according to thewavelength of the applied light is formed in contact with the object inorder to enhance the efficiency of the light irradiation treatment.

A photocatalyst 101 is formed over the gate electrode layer 106, and lowwettability substances 155 a and 155 b are formed over the photocatalyst101 (FIG. 4).

In this embodiment mode, a TiCl₃ solution is applied and baked to form a50 nm thick titanium oxide layer. Alternatively, a titanium nitride(TiO_(X) (typified by TiO₂)) crystal including a predeterminedcrystalline structure may be formed by sputtering. In this case,sputtering is carried out with argon gas and oxygen using a titaniumtube as the target. He gas may be used additionally. A titanium oxidelayer having high photocatalytic activity is formed under an atmospherecontaining much oxygen and higher formation pressure. Further, it ispreferable to form the titanium oxide layer heating the film formationchamber or the substrate provided with the object. The thus formedtitanium oxide layer has photocatalytic properties even though it isthin.

As an example of the composition of the solution for forming thelow-wettability region, a silane coupling agent expressed in a chemicalformula of R_(n)—Si—X_((4−n)) (n=1, 2, 3) is used. Here, R denotes asubstance which contains a comparatively inactive group such as an alkylgroup. Further, X includes a hydrolysable group which can be bonded bythe condensation with a hydroxyl group or absorbed water on a surfacesuch as halogen, a methoxy group, an ethoxy group, or an acetoxy group.

Using a fluorine-based silane coupling agent (fluoroalkylsilane(hereinafter referred to as FAS)) having a fluoroalkyl group for R thatis a representative example of the silane coupling agent, thewettability can be lowered. R of FAS has a structure which is expressedin (CF₃)(CF₂)_(x)(CH₂)_(y) (x: an integer from 0 to 10, y: an integerfrom 0 to 4). In the case where a plurality of R or X are bonded to Si,the R or X may all be the same or different. Fluoroalkylsilane (FAS)such as heptadecafluoro tetrahydrodecyltriethoxysilane,heptadecafluorotetrahydrodecyltrichlorosilane,tridecafluorotetrahydrooctyltrichlorosilane,trifluoropropyltrimethoxysilane are typically used.

As the solvent of a solution for forming the low-wettability region, asolvent which forms a low-wettability region scuh as a hydrocarbon-basedsolvent, tetrahydrofuran, or the like, namely, n-pentane, n-hexane,n-heptane, n-octane, n-decane, dicyclopentane, benzene, toluene, xylene,durene, indene, tetrahydronaphthalene, decahydronaphthalene, squalene,or the like is used.

As an example of the compound of the solvent for forming thelow-wettability region, a material having a fluorocarbon chain (fluorineresin) can be used. As the fluorine resin, polytetrafluoroethylene(PTFE; polytetrafluoroethylene resin), perfluoroalkoxyalkane (PFA;tetrafluoroethylene perfluoroalkylvinylether copolymer resin),perfluoroethylene propylene copolymer (PFEP; tetrafluoroethylenehexafluoropropylene copolymer resin), ethylene-tetrafluoroethylenecopolymer (ETFE; tetrafluoroethylene-ethylene copolymer resin),polyvinylidene fluoride (PVDF; polyvinylidene fluoride resin),polychlorotrifluoroethylene (PCTFE; polytrifluorochloroethylene resin),ethylene-chlorotrifluoroethylene copolymer (ECTFE;polytrifluorochloroethylene-ethylene copolymer resin),polytetrafluoroethylene-perfluorodioxol copolymer (TFE/PDD),polyvinylfluoride (PVF; vinyl fluoride resin), or the like can be used.

In addition, an organic material which does not form a low-wettabilityregion (in other words, which forms a high-wettability region) may beused to form a low wettability region by performing treatment with theuse of CF₄ plasma or the like later. For example, a material in which asoluble resin such as polyvinyl alcohol (PVA) is mixed into a solvent ofsuch as H₂O can be used. In addition, PVA may be mixed with anothersoluble resin may be used. An organic material (an organic resinmaterial) (polyimide, acrylic), a material in which a skeleton is formedby the bond of silicon (Si) and oxygen (O), and which includes anorganic group containing at least hydrogen as a substituent.Alternatively, a fluoro group, an alkyl group, or aromatic hydrocarbonmay be used as the substituent. Even when a material having alow-wettability surface is used, wettability can be further reduced byperforming plasma treatment or the like.

In this embodiment mode, FAS is used as a low wettability substance. Thesubstance is wettable with the composition containing a conductivematerial which later constitutes a source/drain electrode layer. FASused in this embodiment mode is decomposed with light having awavelength of 200 nm or less; however, a glass substrate absorbs anddoes not transmit light with a wavelength of 300 nm or less. Therefore,FAS can not be irradiated with light if a glass substrate is used as thesubstrate. In this embodiment mode, the titanium oxide layer exerting aphotocatalytic effect when exposed to light of 380 nm or less is formed.A metal halide lamp which is an ultraviolet lamp which emits light witha wavelength of 200 nm to 450 nm is used as a light source. Thephotocatalyst can be appropriately selected depending on the wavelengthof the light to be used. In this embodiment mode, a low wettabilitysubstance is selectively formed by a droplet discharge method in thevicinity of the pattern formation region; however, the low wettabilitysubstance may be applied to a wide area (to the entire surface, forexample) by spin coating or the like, and patterning may be carried outthereafter. When a droplet discharge method is used as in thisembodiment mode, the waste of material can be reduced, and theefficiency in the use of the material is improved.

Next, the photocatalyst 101 is irradiated with light 171 a and light 171b through the light transmitting substrate 100 as shown FIGS. 5B and 5C.The low wettability substance 155 a and the low wettability substance155 b are decomposed by the energy generated when the photocatalyst 101is activated by the light 171 a and 171 b; thus, the wettability isimproved. The treatment efficiency can be enhanced since thephotocatalytic effect of the photocatalyst is used. The gate electrodelayers 103 and 104 are used as masks; therefore, the surfaces of the lowwettability substance over the regions which are overlapped with thegate electrode layers 103 and t 104 are not modified. High wettabilityregions 151 a and 151 b, which are relatively more wettable, and a lowwettability region 150 that is relatively less wettable are formed onthe surface of the low wettability substance 155 a by light irradiation(FIG. 5B). In the similar manner, a relatively high wettability region153 a, a high wettability region 153 b, and low wettability region 152that is relatively less wettable are formed on the surface of the lowwettability substance 155 b by irradiation with the light 171 a (FIG.5C). The range of options for light is increased since a photocatalystcan be selected in accordance with the light. Consequently, thewavelength that is hardly absorbed by the substance to be provided withthe object can be selected, and light irradiation for controllablesurface modification treatment (so-called back exposure) can be carriedout. Further, the efficiency of light irradiation can be improved, sothat the treatment can be completed even though the light itself has lowenergy. As a result, the apparatuses and steps are simplified, thus,costs and time are reduced, and the production efficiency can beimproved.

In this embodiment mode, when the mask is formed by a droplet dischargemethod, treatment for forming a pattern forming region and the peripherythereof to have different wettability may be performed for pretreatment.In the present invention, when a pattern is formed by discharging adroplet by a droplet discharge method, the pattern shape can becontrolled by forming a low-wettability region and a high-wettabilityregion in a pattern forming region. Performing the treatment on thepattern formation region causes difference in wettability therein, sothat a droplet remains only on the high-wettability region. Accordingly,the pattern can be formed with good control. This step is applicable topretreatment for forming any pattern in the case of using a liquidmaterial.

A mask comprising an insulator such as a resist or polyimide is formedby using a droplet discharge method. An opening 145 is formed in a partof the gate insulating layer 106 by etching using the mask, and a partof the gate electrode layer 104 disposed in the lower layer is exposed.Either plasma etching (dry etching) or wet etching may be adopted forthe etching. However, plasma etching is suitable to treat a largesubstrate. A fluorine-based such as CF₄, NF₃, or chlorine-based gas suchas Cl₂, or BCl₃ is used as the etching gas, and an inert gas such as Heor Ar may be appropriately added. In addition, a local discharge processcan be performed when an atmospheric pressure discharge etching processis applied, and a mask layer need not be entirely formed over thesubstrate.

A composition containing a conductive material is discharged fromdroplet discharge systems 180 a and 180 b to high-wettability regions151 a, 151 b, 153 a, and 153 b. Thus, source/drain electrode layers 111,112, 113, and 114 are formed (FIGS. 6A to 6C). Even when the patternforming material can not be discharged precisely depending on the sizeof the discharge opening of the nozzle from which the droplet isdischarged or the moving ability of the discharge opening, the dropletis attached only to the region to form a desired pattern by performingtreatment for enhancing wettability on the pattern formation region.This is because the pattern formation region and the periphery thereofhave different wettability; therefore, the droplet is repelled only inthe low-wettability region and remains on the pattern formation regionhaving higher wettability. In other words, a droplet is repelled by thelow-wettability region surrounding a periphery of the high-wettabilityregion; therefore, the boundary between the high-wettability region andthe low-wettability region functions as a partition wall (a bank).Accordingly, even the composition containing a conductive materialhaving fluidity can remain on the high-wettability region; thus, eachsource/drain electrodelayer can be formed to have a desired shape.

The source/drain electrode layer 111 also serves as a source wiringlayer, and the source/drain electrode layer 113 also serves as a powersupply line.

The source/drain electrode layers 111 to 114 can be formed in a similarmanner as the above described gate electrode layers 103 and 104.

As a conductive material for forming the source/drain electrode layers111, 112 113, and 114, a compound which mainly contains metal particlesof Ag (silver), Au (gold), Cu (copper), W (tungsten), Al (aluminum), orthe like can be used. Alternatively, indium tin oxide (IFO), ITSOincluding indium tin oxide and silicon oxide, organic indium, organotin,zinc oxide, titanium nitride, or the like having light-transmittingproperties may be combined.

The source/drain electrode layer 112 and the gate electrode layer 104are electrically connected to each other through the opening 145 formedin the gate insulating layer 106. A part of the source/drain electrodelayer forms a capacitor element (FIG. 6B)

According to the present invention, in forming a fine pattern, forexample an electrode layer, the pattern can be formed on the patternformation region without a droplet extended over the region even thougha droplet discharge opening is somewhat large. Therefore, defects suchas short that is caused when the droplet is applied to the area otherthan the pattern formation region can be prevented. Further, thethickness of the wiring can also be controlled. When the surfacemodification is carried out by the light irradiation from the substrateside as in this embodiment mode, a large area can be treated in additionto that the pattern can be formed with good control; thus, theproduction efficiency is improved. By combining a droplet dischargemethod, the material loss can be avoided compared with entire surfaceapplication formation by spin coating or the like; therefore, the costcan be reduced. According to the present invention, a pattern can beformed with good control even in the case where a wiring or the like isprovided integrally and intricately due to miniaturization and thinnerfilm formation.

As pretreatment, an organic material which functions as an adhesiveagent may be formed to enhance adhesion with a pattern formed by adroplet discharge method. In this case, regions having differentwettability may be formed over the material. An organic material (anorganic resin material) (polyimide, acrylic), a material in which askeleton is formed by the bond of silicon (Si) and oxygen (O), and whichincludes an organic group containing at least hydrogen as a substituent.Alternatively, a fluoro group, an alkyl group, or aromatic hydrocarbonmay be used as the substituent.

Next, a semiconductor layer is formed. A semiconductor layer having oneconductivity may be formed if necessary. Also, an NMOS structure of ann-channel TFT in which an n-type semiconductor layer is formed, a PMOSstructure of a p-channel TFT in which a p-type semiconductor layer isformed, and a CMOS structure of an n-channel TFT and a p-channel TFT canbe manufactured. In addition, the n-channel TFT and the p-channel TFTcan be formed by adding an element which provides conductivity withdoping to provide conductivity to form an impurity region in thesemiconductor layer.

The semiconductor layer can be formed by a known technique (sputtering,LPCVD, plasma CVD, or the like). The material for a semiconductor layeris not limited, and a silicon germanium (SiGe) alloy or the like may beused.

The semiconductor layer is formed using an amorphous semiconductor(typically, hydrogenated amorphous silicon), a crystalline semiconductor(typically, polysilicon), or a semiamorphous semiconductor. Polysilicon(polycrystalline silicon) includes a so-called high temperaturepolysilicon using polysilicon which is formed at a temperature of 800°C. or more as a main material, a so-called low temperature polysiliconusing polysilicon which is formed at a temperatures of 600° C. or lessas a main material, polysilicon crystallized by being added with anelement or the like which promotes crystallization, or the like.

As another material, a semiamorphous semiconductor or a semiconductorwhich contains a crystal phase in a part of the semiconductor layer canalso be used.

When a crystalline semiconductor layer is used as the semiconductorlayer, a known method (laser crystallization, heat crystallization, aheat crystallization method using an element promoting crystallizationsuch as nickel, or the like) may be employed as a method formanufacturing the crystalline semiconductor layer. A microcrystal whichis a SAS can be crystallized by being irradiated with laser light toenhance the crystallinity. In the case where an element promotingcrystallization is not used, the hydrogen is released until hydrogenconcentration contained in an amorphous silicon film becomes 1×10²⁰atoms/cm³ or less by heating the amorphous silicon film for one hour ata temperature of 500° C. in a nitrogen atmosphere before irradiating theamorphous silicon film with laser light. This is because a film isdamaged when the amorphous silicon film containing much hydrogen isirradiated with laser light.

Any method can be used for introducing a metal element into theamorphous semiconductor layer without limitation as long as the methodis capable of making the metal element exist on the surface or insidethe amorphous semiconductor layer. For example, a sputtering method,CVD, plasma treatment (including plasma CVD), an adsorption method, or amethod for applying a metal salt solution can be employed. Among them,the method using a solution is simple and easy and is advantageous interms of easy concentration adjustment of the metal element. It ispreferable to form an oxide film by UV light irradiation in oxygenatmosphere, a thermal oxidation method, treatment with ozone water orhydrogen peroxide including a hydroxyl radical, or the like in order toimprove wettability of the surface of the amorphous semiconductor layerand to spread the aqueous solution over the entire surface of theamorphous semiconductor layer.

In addition, heat treatment and laser light irradiation may be combinedto crystallize the amorphous semiconductor layer. Alternatively, theheat treatment and/or the laser light irradiation may be independentlyperformed plural times.

A crystalline semiconductor layer may be directly formed over thesubstrate by a linear plasma method. Alternatively, a crystallinesemiconductor layer may be selectively formed over the substrate byusing a linear plasma method.

A semiconductor region can be formed from an organic semiconductormaterial by a printing method, a spray method, spin coating, a dropletdischarge method, or the like. In this case, since the above etchingstep is not required, the number of steps can be reduced. A lowmolecular weight material, a high molecular weight material, or the likeis used for the organic semiconductor, and in addition, a material suchas an organic pigment, a conductive high molecular weight material canbe used. A π-electron conjugated high molecular weight material having askeleton constituted by a conjugated double bonds is preferably used asan organic semiconductor material used in the present invention.Typically, a soluble high molecular weight material such aspolythiophene, polyfluoren, poly(3-alkylthiophene), a polythiophenederivative or pentacene can be used.

A material with which a first semiconductor region can be formed byperforming treatment after depositing a soluble precursor is given as anexample of an organic semiconductor material which can be used accordingto the present invention. Note that polythienylenevinylene,poly(2,5-thienylenevinylene), polyacetyrene, polyacetyrene derivative,polyallylenevinylene or the like is given as an example of such anorganic semiconductor material formed by using the precursor.

In converting the precursor to an organic semiconductor, a reactioncatalyst such as a hydrogen chloride gas is added additionally to a heattreatment. The following can be applied as a typical solvent whichdissolves the organic semiconductor material having solubility: toluene,xylene, chlorobenzene, dichlorobenzene, anisole, chloroform,dichloromethane, γ butyl lactone, butyl cellosolve, cyclohexane, NMP(N-methyl-2-pyrrolidone), cyclohexanone, 2-butanone, dioxane,dimethylformamide (DMF), THF (tetrahydrofuran) or the like.

In this embodiment mode, a treatment for improving the wettability ofthe low wettability regions 150 and 152 by light irradiation is carriedout. Subsequently, the semiconductor layers 107 and 108 are formed by adroplet discharge method using pentacene (FIGS. 7A to 7C).

Then, a first electrode layer 117 is formed by selectively discharging acomposition containing a conductive material over the gate insulatinglayer 106 (FIGS. 8A to 8C). When the first electrode layer 117 isformed, naturally, pretreatment for forming a low-wettability region anda high-wettability region may be performed. The first electrode layer117 can be formed with better control and more selectively bydischarging a composition containing a conductive material over thehigh-wettability region. When light is emitted from thelight-transmitting substrate 100 side, or when a transmissive displaypanel is manufactured, the first electrode layer 117 may be formed byforming a predetermined pattern using a material including indium tinoxide (ITO), indium tin oxide containing silicon oxide (ITSO), indiumzinc oxide (IZO) containing zinc oxide (ZnO), zinc oxide (ZnO), amaterial in which gallium (Ga) is doped in ZnO, or tin oxide (SnO₂) orthe like, and by baking the pattern.

Preferably, the first electrode layer 117 may be formed of indium tinoxide (ITO), indium tin oxide containing silicon oxide (ITSO), zincoxide (ZnO), or the like by sputtering. It is more preferable to useindium tin oxide containing silicon oxide formed by sputtering using atarget of ITO containing silicon oxide of from 2% to 10% by weight. Inaddition, a conductive material in which ZnO is doped with gallium (Ga),or an oxide conductive material which contains silicon oxide and inwhich indium oxide is mixed with zinc oxide (ZnO) of from 2% to 20% byweight may be used. After the first electrode layer 117 is formed bysputtering, a mask layer may be formed by a droplet discharge method,and a desired pattern may be formed by etching. In this embodiment mode,the first electrode layer 117 is formed of a light-transmittingconductive material by a droplet discharge method. Specifically, it isformed using indium tin oxide or ITSO made of ITO and silicon oxide.

In this embodiment mode, above described is an example of the gateinsulating layer comprising three layers of a silicon nitride film, asilicon oxynitride film (silicon oxide film), a silicon nitride film. Asa preferable structure, the first electrode layer 117 comprising indiumtin oxide containing silicon oxide is preferably formed close in contactwith the insulating layer comprising silicon nitride included in thegate insulating layer 106. Accordingly, an effect of increasing a rateat which light generated in an electroluminescent layer is emittedoutside can be exerted. The gate insulating layer may be interposedbetween the gate wiring layer or the source/drain electrode layer andthe first electrode layer and may function as a capacitor element.

The first electrode layer 117 can be selectively formed over the gateinsulating layer 106 before forming the source/drain electrode layer114. In this case, this embodiment mode has a connection structure inwhich the source/drain electrode layer 114 is laminated over the firstelectrode layer 117. When the first electrode layer 117 is formed beforeforming the source/drain electrode layer 114, it can be formed over aflat region. Therefore, the first electrode layer 117 can be formed tohave preferable planarity since preferable coverage and depositionproperties can be obtained and polishing treatment such as CMP can becarried out sufficiently.

A structure in which an interlayer insulating layer is formed over thesource/drain electrode layer 114 to be electrically connected to thefirst electrode layer 117 through a wiring layer may be also employed.In this case, instead of forming an opening (contact hole) by removingthe insulating layer, a substance having low wettability with respect tothe insulating layer is formed over the source/drain electrode layer114. The insulating layer is formed on a region except for a regionwhere the substance having low wettability is formed when a compositioncontaining an insulator is applied by a coating method or the like.

After forming the insulating layer by solidifying it by heating, drying,or the like, the substance having low wettability is removed to form theopening. The wiring layer is formed so as to fill the opening, and thefirst electrode layer 117 is formed so as to be in contact with thewiring layer. With this method, etching is not necessarily performed toform the opening; therefore, the process can be simplified.

When an EL display panel is manufactured or in the case of a structurein which generated light is emitted to the side opposite to thelight-transmitting substrate 100 side, a compound which mainly containsmetal particles of Ag (silver), Au (gold), Cu (copper), W (tungsten), orAl (aluminum), or the like can be used. Alternatively, the firstelectrode layer 117 may be formed by forming a transparent conductivefilm or a conductive film having light reflectivity by sputtering,forming a mask pattern by a droplet discharge method, and then combiningetching.

The first conductive layer 117 may be polished by CMP or by cleaningwith polyvinyl alcohol-based porous body so that the surface of thefirst conductive layer 117 is made flat. In addition, after polishing byCMP, ultraviolet irradiation or oxygen plasma treatment or the like maybe performed on the surface of the first electrode layer 117.

According to the above-mentioned steps, the TFT substrate for a displaypanel in which a TFT of a bottom gate type and a pixel electrode areconnected to the light-transmitting substrate 100 is completed. The TFTin this embodiment mode is a co-planar type. The TFT shown in thisembodiment mode can be manufactured in a self-aligned manner accordingto the present invention.

Subsequently, an insulating layer (also referred to as a partition wallor a bank) 121 is selectively formed (FIG. 9A). The insulating layer 121is formed to have an opening over the first insulating layer 117. Inthis embodiment mode, the insulating layer 121 is formed over the entiresurface, and etched and patterned by using a mask of a resist or thelike. When the insulating layer 121 is formed by a droplet dischargemethod or a printing method which can form the insulating layer 121directly and selectively, patterning by etching is not necessarilyrequired. The insulating layer 121 can also be formed to have a desiredshape by pretreatment according to the present invention.

The insulating layer 121 can be formed of silicon oxide, siliconnitride, silicon oxynitride, aluminum oxide, aluminum nitride, aluminumoxynitride or another inorganic insulating material; acrylic acid,methacrylic acid, or a derivative thereof; a heat-resistant polymer suchas polyimide, polybenzimidazole; or an organic siloxane-based insulatingmaterial in which an organic group such as methyl or phenyl issubstituted for hydrogen bound with silicon or an inorganicsiloxane-based material, each of which contains the Si—O—Si bond among acompound including silicon, oxygen and hydrogen, which is formed byusing a siloxane material as a start material. The insulating layer 121may be also formed by using a photosensitive material such as acrylic orpolyimide, or a non-photosensitive material. The insulating layer 121preferably has a shape in which a radius curvature changes continuously.Accordingly, the coverage of an electroluminescent layer 122 and asecond electrode layer 123 which are formed over the insulating layer121 is enhanced.

After forming the insulating layer 121 by discharging a compound by adroplet discharge method, the surface of the insulating layer may bepressed with pressure to planarize in order to enhance its planarity. Asa pressing method, unevenness may be smoothed by making a roller-shapedobject moved over the surface, or the surface may be vertically pressedwith a flat plate-shaped object. A heat process may be performed at thetime of pressing. Alternatively, unevenness on the surface may beeliminated with an air knife by softening or melting the surface with asolvent or the like. A CMP method may be also used for polishing thesurface. This step may be applied for planarizing a surface whenunevenness is caused by a droplet discharge method. When the planarityis enhanced through the step, display variations or the like of thedisplay panel can be prevented; therefore, a high-definition image canbe displayed.

A light emitting element is formed over the substrate 100 having a TFTfor a display panel (FIG. 9B).

Before forming the electroluminescent layer 122, moisture in the firstelectrode layer 117 and the insulating layer 121 or adsorbed eachsurface is removed by performing heat treatment at a temperature of 200°C. under atmospheric pressure. It is preferable to perform heattreatment at temperatures of from 200° C. to 400° C., preferably from250° C. to 350° C. under low pressure, and to form theelectroluminescent layer 122 without being exposed to atmospheric air bya vacuum evaporation method or a droplet discharge method which isperformed under low pressure.

As the electroluminescent layer 122, materials each produces theluminescence of red (R), green (G), and blue (B) is selectively formedby an evaporation method using an evaporation mask or the like for each.The materials (low molecular weight materials, high molecular weightmaterials, or the like) each produces luminescence of red (R), green (G)and blue (B) can be formed by a droplet discharge method in the samemanner as a color filter. This case is preferable since separatecoloring of RGB can be carried out even without using a mask. Then, thesecond electrode layer 123 is formed over the electroluminescent layer122 to complete a display device having a display function using a lightemitting element.

Although it is not shown, it is effective to provide a passivation filmso as to cover the second electrode layer 123. A protective film whichis provided at the time of forming a display device may have a singlelayer structure or a layer structure. As the passivation film, a singlelayer of an insulating film containing silicon nitride (SiN), siliconoxide (SiO₂), silicon oxynitride (SiON), silicon nitride oxide (SiNO),aluminum nitride (AlN), aluminum oxynitride (AlON), aluminum nitrideoxide (AlNO) which has more nitrogen content than oxygen content,aluminum oxide, diamond like carbon (DLC) or a nitrogen-containingcarbon film (CN_(x)), or a laminated layer in which the insulating filmsare combined can be used. For example, a laminated layer such as anitrogen-containing carbon film (CN_(x)) and silicon nitride (SiN) or anorganic material can be used, or a laminate of a polymer such as astyrene polymer may be used. Alternatively, a material which has askeleton formed by the bond of silicon (Si) and oxygen (O), and whichincludes at least hydrogen as a substituent, or at least one offluorine, an alkyl group, and aromatic hydrocarbon as a substituent maybe also used.

At this time, it is preferable to use a film having good coverage as thepassivation film, and a carbon film. Particularly, a DLC film iseffective. A DLC film can be formed within the temperatures ranging fromroom temperature to 100° C. or lower; therefore, a DLC film can beeasily formed over an electroluminescent layer having low heatresistance. A DLC film can be formed by a plasma CVD method (typically,RF plasma CVD, microwave CVD, electron cyclotron resonance (ECR) CVD,thermal filament CVD, or the like), a combustion flame method,sputtering, ion beam deposition, laser deposition, or the like. Ahydrogen gas and a hydrocarbon-based gas (for example CH₄, C₂H₂, C₆H₆,or the like) are used as a reactive gas which is used for forming thefilm. The reaction gas is ionized by glow discharge. The ions areaccelerated to collide with a cathode applied with negative self bias. ACN film may be formed by using a C₂H₂ gas and an N₂ gas as the reactivegas. The DLC film has a high blocking effect on oxygen and can suppressthe oxidation of the electroluminescent layer. Accordingly, theelectroluminescent layer can be prevented from oxidizing during thesubsequent sealing step.

Subsequently, a sealant is formed and sealing is performed with asealing substrate. Then, a flexible wiring substrate may be connected toa gate wiring layer which is formed being electrically connected to thegate electrode layer 103 to electrically connect to the exterior. Thisis the same for a source wiring layer which is formed being electricallyconnected to the source/drain electrode layer 111.

A completion drawing of an EL display panel manufactured according tothe present invention is shown in FIGS. 18A and 18B. FIG. 18A shows atop view of the EL display panel and FIG. 18B shows a cross-sectionalview taken along line E-F in FIG. 18A. In FIGS. 18A and 18B, a pixelportion 3301 formed over an element substrate 3300 includes a pixel3302, gate wiring layers 3306 a and 3306 b, and a source wiring layer3308, and the element substrate 3300 is fixed with a sealing substrate3310 by being bonded with a sealant 3303. In this embodiment mode, adriver IC 3351 is provided over an FPC 3350 and mounted by TAB.

As shown in FIGS. 18A and 18B, desiccants 3305, 3304 a, and 3304 b areprovided in a display panel in order to prevent deterioration due tomoisture of the element. The desiccant 3305 is formed so as to encirclethe circumference of the pixel portion, and the desiccants 3304 a and3304 b are formed in a region corresponding to the gate wiring layers3306 a and 3306 b. In this embodiment mode, the desiccants are providedin a depression formed in the sealing substrate, which does not preventan EL display panel from being thinned. A large water absorption areacan be obtained since a desiccant is formed also in a regioncorresponding to a gate wiring layer, thereby enhancing absorptionefficiency. Additionally, since the desiccants are formed over the gatewiring layer which does not emit light directly, a light extractionefficiency is not deteriorated. In this embodiment mode, a filler 3307is filled in the display panel. When a hygroscopic substance such as adesiccant is used as the filler, further absorption effect can beobtained and the element can be prevented from being deteriorated.

In this embodiment mode, the case where a light emitting element issealed with a glass substrate is shown. Sealing treatment is treatmentto protect a light emitting element from moisture. Therefore, any of amethod in which a light emitting element is mechanically sealed with acover material, a method in which a light emitting element is sealedwith a thermosetting resin or an ultraviolet curable resin, and a methodin which a light emitting element is sealed with a thin film of such asmetal oxide, nitride or the like having high barrier capabilities, canbe used. As for the cover material, glass, ceramics, plastic, or metalcan be used. However, when light is emitted to the cover material side,the cover material needs to have light-transmitting properties. Enclosedspace is formed by attaching the cover material to the substrate overwhich the above-mentioned light emitting element is formed with asealant such as a thermosetting resin or an ultraviolet curable resinand then by curing the resin with heat treatment or ultravioletirradiation treatment. It is also effective to provide a hydroscopicabsorbent material typified by barium oxide in the enclosed space. Theabsorbent material may be provided over the sealant or over a partitionwall or a peripheral part so as not to block light emitted from a lightemitting element. Further, it is also possible to fill the space betweenthe cover material and the substrate over which the light emittingelement is formed with a thermosetting resin or anultraviolet-light-curable resin. In this case, it is effective to add ahydroscopic material typified by barium oxide in the thermosetting resinor the ultraviolet-light-curable resin.

In this embodiment mode, although a single gate structure of a switchingTFT is shown, a multi-gate structure such as a double gate structure maybe also employed. When a semiconductor is manufactured by using a SAS ora crystalline semiconductor, an impurity region can be formed by addingan impurity which imparts one conductivity type. In this case, asemiconductor layer may have an impurity region having differentconcentration. For example, the semiconductor layer may have a lowconcentration impurity region in the periphery of a channel formationregion and a region which is laminated with a gate electrode layer, anda high concentration impurity region which is outside thereof.

As described above, in this embodiment mode, photolithography using aphotomask is not employed, and thus steps can be omitted. In addition, adisplay panel can be easily manufactured by directly forming variouspatterns over the substrate with the use of a droplet discharge methodeven when a glass substrate which is in and after the fifth generationhaving 1000 mm or more on a side is used.

According to the present invention, a desired pattern can be formed withgood control, and the material loss and the cost can be reduced. Hence,a high-performance and highly reliable display device can bemanufactured with high yield.

EMBODIMENT MODE 3

An embodiment mode of the present invention will be described withreference to FIGS. 10A to 10C and FIGS. 11A and 11B. In this embodimentmode, a display device is manufactured by using a top gate type (aninverted staggered type) thin film transistor as a thin film transistor.An example of a liquid crystal display device using a liquid crystalmaterial as a display element is shown. Accordingly, the same part or apart having similar function will not be repeatedly explained. Note thatFIGS. 10A to 10C and FIGS. 11A and 11B show cross-sectional views of thedisplay device.

Also in this embodiment mode, light irradiation is carried out through asubstrate to modify the irradiated area to change the wettabilitythereof by utilizing the photo activity of a photocatalyst.

A source/drain electrode layer 330 and a source/drain electrode layer308 are formed over a light-transmitting substrate 300. The electrodelayers are formed by a droplet discharge method in this embodiment mode.

An n-type semiconductor layer is formed over the source/drain electrodelayers 330 and 308 and is etched with a mask formed of a resist or thelike. The resist may be formed by using a droplet discharge method. Asemiconductor layer is formed over the n-type semiconductor layer andpatterned by using a mask or the like again. Accordingly, n-typesemiconductor layers 307 and 306 are formed. The semiconductor layer 306is made of silicon which is an inorganic material; however, it can alsobe formed with an organic semiconductor such as the above pentacene.When an organic semiconductor is selectively formed by a dropletdischarge method or the like, the patterning process can be simplified.

Then, a gate insulating layer 305 is formed to be a single layer or alaminate by plasma CVD or sputtering (FIG. 10A). The gate insulatinglayer 305 may use either an inorganic material or an organic material.As a preferable mode, in particular, a laminate of three layers of aninsulating layer 305 a including silicon nitride, an insulating layer305 b including silicon oxide, and an insulating layer 305 c includingsilicon nitride is equivalent to the gate insulating layer.

A photocatalyst 350 is formed over a gate insulating layer 305. A lowwettability substance 351 is formed in the vicinity of the area of thephotocatalyst 350 where the gate electrode layer is to be formed (FIG.10B).

Next, a mask constituted by a resist or the like is formed over thephotocatalyst 350, and the photocatalyst 350 and the gate electrodelayer 305 are etched to form an opening 345. In this embodiment, themask is selectively formed by a droplet discharge method.

The photocatalyst 350 is irradiated with light 371 from a light source370 through the light-transmitting substrate 300. The light 371penetrates the substrate 300, the semiconductor layer 306, and the gateinsulating layer 305, and activates the photocatalyst 350, so that thesurface of the low wettability substance 351 is modified by the energythereof. The source/drain electrode layers 330 and 308 are used asmasks; thus, a relatively higher wettability region 301, lowerwettability regions 302 a and 302 b are formed on the surface of the lowwettability substance 351 (FIG. 10C). The treatment efficiency and thetreatment capacity are enhanced with the use of the photocatalyst. If afilm is modified by light irradiation using a source/drain electrodelayer as a mask as in this embodiment mode, fine patterns havingdifferent wettability can even be formed with good control. Further, incombination with a droplet discharge method, material loss can beavoided and the cost can be reduced compared with the case of entiresurface coating such as spin coating or the like.

In this embodiment mode, a photocatalyst is formed over thelight-transmitting substrate 300, the semiconductor layer 306, and thegate insulating layer 305 and is irradiated with light therethrough,thereby modifying the surface of the substance formed in contact withthe photocatalyst. Accordingly, it is important that the lightabsorption in the light-transmitting substrate 300, the semiconductorlayer 306, and the gate insulating layer 305 is suppressed, in order toacquire energy due to photo activity of the photocatalyst, that isrequired for modifying the surface of the formation region of the gateelectrode layer. The energy used for modifying the substance surfacevaries in accordance with the energy absorbed in the substancetransmitting light. Thus, the film thickness and the light intensity maybe set appropriately.

A composition containing a conductive material is discharged in themobile form of droplets from a droplet discharge system 381 as to thehigh wettability region 301 to form a gate electrode layer 303 (FIG.11A). The discharged mobile composition containing a conductive materialis repelled by the low wettability regions 302 a and 302 b due to thedifference of the wettability of the gate formation region without beingfixed thereto. Therefore, the composition is formed in the highwettability region 301, which is more stable, with good control andstability.

The photocatalyst which has been formed for pretreatment after theformation of the electrode layer and the substance which changes thewettability may be left, or an unnecessary portion may be removed afterthe formation of the pattern. The removal may be carried out by ashingwith oxygen, etching, plasma treatment, or the like using the pattern asa mask.

A pixel electrode layer 311 is formed by a droplet discharge method. Thepixel electrode layer 311 and the source/drain electrode layer 308 areelectrically connected to each other through the opening 345 formed inadvance. The same material used for the above-mentioned first electrodelayer 117 can be used for the pixel electrode layer 311. When atransmissive liquid crystal display panel is manufactured, apredetermined pattern is formed with a composition including indium tinoxide (ITO), indium tin oxide containing silicon oxide (ITSO), zincoxide (ZnO), tin oxide (SnO₂) or the like, and the pattern is baked toform the pixel electrode layer 311.

An insulating layer 312 called an alignment film is formed by a printingmethod or spin coating so as to cover the pixel electrode layer 311. Theinsulating layer 312 can be selectively formed with the use of a screenprinting method or an offset printing method. Then, rubbing isperformed. A sealant is formed in at the peripherally of the regionwhere a pixel is formed by a droplet discharge method (not shown).

Subsequently, a liquid crystal display panel can be manufactured byattaching a counter substrate 324 provided with an insulating layer 321functioning as an alignment film, a coloring layer 322 functions as acolor filter, a conductive layer 323 functioning as a counter electrode,and the counter substrate 324 provided with a polarizing plate 325 tothe TFT substrate 300 with a spacer therebetween, and by providing thespace with a liquid crystal layer 320 (see FIG. 11B). A sealant may bemixed with a filler, and further, the counter substrate 324 may beprovided with a shielding film (a black matrix), or the like. Note thata dispenser type (a dropping type) or a dip type (a pumping type) bywhich a liquid crystal is injected utilizing capillary phenomenon afterattaching the counter substrate 324 can be used as a method for formingthe liquid crystal layer.

A liquid crystal drop injection method employing a dispenser type willbe described with reference to FIG. 29. A liquid crystal drop injectionmethod shown in FIG. 29 includes a control device 40, an imaging means42, a head 43, a liquid crystal 33, markers 35 and 45, a barrier layer34, a sealant 32, a TFT substrate 30, and a counter substrate 20. Aclosed loop is formed with the sealant 32, and the liquid crystal 33 isdropped once or plural times therein from the head 43. When the liquidcrystal material is highly adhesive, the liquid crystal material iscontinuously discharged and attached to a liquid crystal formationregion with being interconnected. On the other hand, when the liquidcrystal material is low adhesive, the liquid crystal material isintermittently discharged and a droplet is dropped as in FIG. 29. Atthis time, the barrier layer 34 is provided to prevent the sealant 32and the liquid crystal 33 from reacting with each other. Subsequently,the substrates are attached in vacuum, and then, ultraviolet curing isperformed to make the space filled with the liquid crystal.

A connection portion is formed to connect the pixel portion formedthrough the above steps and an external wiring substrate. The insulatinglayer in the connection portion is removed by ashing treatment using anoxygen gas under the atmospheric pressure or pressure in proximity ofthe atmospheric pressure. This treatment is performed by using an oxygengas and one or more gases of hydrogen, CF₄, NF₃, H₂O, and CHF₃. In thisstep, ashing treatment is performed after sealing by using the countersubstrate to prevent damage or destruction due to static, however,ashing treatment may be performed at any timing when there are feweffects of static.

A connection wiring substrate is provided so as to electrically connecta wiring layer with an anisotropic conductive layer interposedtherebetween. The wiring substrate has a function of transmitting asignal or electric potential from the external. Through theabove-mentioned steps, a liquid crystal display panel including adisplay function can be manufactured.

In this embodiment mode, a switching TFT having a single gate structureis described, however, a multi gate structure such as a double gatestructure may be employed. When a semiconductor layer is manufacturedwith the use of a SAS or crystalline semiconductor, an impurity regioncan be formed by adding an impurity which provides one conductivitytype. In this case, the semiconductor layer may have impurity regionshaving different concentrations. For example, the periphery of a channelregion of a semiconductor layer, which forms a laminate with a gateelectrode layer and may be a low concentration impurity region, and theouter region thereof may be a high concentration impurity region.

As described above, the steps can be reduced in this embodiment mode bynot applying a light exposure step using a photomask. In addition, adisplay panel can be easily manufactured by directly forming variouspatterns over a substrate with a droplet discharge method even when aglass substrate in and after the fifth generation having 1000 mm or moreon a side is used.

According to the present invention, a desired pattern can be formed withgood control, and the material loss and the cost can be reduced. Hence,a high-performance and highly reliable display device can bemanufactured with high yield.

EMBODIMENT MODE 4

A thin film transistor can be formed by applying the present invention,and a display device can be formed with the use of the thin filmtransistor. In addition, when a light emitting element is used and ann-type transistor is used as a transistor which drives the lightemitting element, light emitted from the light emitting element performsany of bottom emission, top emission, and dual emission. Here, alaminated structure of a light emitting element of each emission will bedescribed with reference to FIGS. 12A to 12C.

Further, in this embodiment mode, channel protective thin filmtransistors 471 (FIG. 12C) and 481 (FIG. 12A), and a channel etch thinfilm transistor 461 (FIG. 12B) according to the present invention areused. The thin film transistor 481 is provided over a light-transmittingsubstrate 480 and constituted by a gate electrode layer 493, a gateinsulating layer 497, a semiconductor layer 494, an n-type semiconductorlayer 495, a source/drain electrode layer 487, and a channel protectivelayer 496. In this embodiment mode, a silicon film having an amorphousstructure is used as the semiconductor layer, and an n-typesemiconductor layer is used as a semiconductor layer of one conductivitytype. Instead of forming an n-type semiconductor layer, a semiconductormay be given conductivity by plasma treatment using a PH₃ gas. Thesemiconductor layer is not limited to the mode of this embodiment mode,and a crystalline semiconductor layer may be used as in Embodiment Mode2. In the case of using a crystalline semiconductor layer of polysiliconor the like, an impurity region having one conductivity type may beformed by doping (adding) impurities into the crystalline semiconductorlayer without forming the one conductivity type semiconductor layer.Further, an organic semiconductor of such as pentacene can be formed.For example, when an organic semiconductor is selectively formed by adroplet discharge method, the patterning process can be simplified.

A photocatalyst 499 and a low wettability substance 490 are formed overthe channel protective layer 496 and the n-type semiconductor layer 495.In this embodiment mode, the photocatalyst 499 is irradiated with lightfrom the light-transmitting substrate side without being blocked by thegate electrode layer 493, thereby activating the photocatalyst 499 andmodifying a surface of the low wettability substance 490. Light with awavelength by which the photocatalyst is activated is applied as thelight. The modification capacity by light irradiation is enhanced by theenergy due to the activation of the photocatalyst. The range of optionsfor the wavelength of light to be applied is increased by selecting anappropriate photocatalyst; thus, light with wavelength that is notabsorbed by the light-transmitting substrate can be applied.

In this embodiment mode, a surface of the low wettability substance 490that is less wettable with a composition containing a conductivematerial, except where the gate electrode layer 493 is overlapped withthe channel protective film 496 to be a mask, is modified to be morewettable by means of light irradiation. Consequently, high wettabilityregions 492 a and 492 b that are relatively more wettable, and a lowwettability region 491 that is relatively less wettable is formed over asurface of the low wettability substance 490. The composition containinga conductive material does not fix to the low wettability region 491 onthe surface of the channel protective layer since it is less wettablethan the high wettability regions 492 a and n 492 b on the surface ofthe n-type semiconductor on the periphery of the low wettability region491. Consequently, the source/drain electrode layer 487 is formed overthe high wettability regions 492 a and 492 b, which are more wettable,with good control. Since the low wettability substance used in thisembodiment mode is FAS that is thin as a molecular level, the n-typesemiconductor layer and the electrode layers are not insulated. The lowwettability substance can be made conductive or insulative by selectingthe material and/or the thickness in according with the structure to beused.

As to the thin film transistor 481, a substance that is less wettablewith the composition containing a conductive material is formed over thechannel protective layer. When the substance has low wettability alsowith an insulating layer 498 formed to cover the thin film transistor481, formation defects such as that the adhesion of the insulating layer498 is reduced would be caused. Therefore, it is preferable to removethe low wettability substance or to modify the substance to improve thewettability by light irradiation. Such treatment is not necessarilycarried out in the case where the insulating layer is formed by vapordeposition, CVD, sputtering, or the like. The insulating layer coveringthe thin film transistor 481 shown in FIG. 12A is formed by vapordeposition, which is an example where the low wettability substance overthe channel protective layer is not modified. FIG. 12C shows an examplein which the low wettability region 491 is irradiated with light toimprove the wettability before forming the insulating layer 478 sincethe insulating layer 478 covering the thin film transistor 471 is formedby the droplet discharge method.

A channel protective layer 496 may be formed by a droplet dischargemethod using polyimide, polyvinyl alcohol or the like. As a result, aphotolithography step can be omitted. The channel protective layer maybe formed from one or more of an inorganic material (silicon oxide,silicon nitride, silicon oxynitride, silicon nitride oxide or the like),a photosensitive or non-photosensitive organic material (an organicresin material) (polyimide, acrylic, polyamide, polyimide amide, aresist, benzocyclobutene or the like), a Low k material which has a lowdielectric constant, and the like; a laminate of such films; or thelike. Additionally, a material which has a skeleton formed by the bondof silicon (Si) and oxygen (O), and which includes at least hydrogen asa substituent, or at least one of fluoride, an alkyl group, and aromatichydrocarbon as a substituent, may be used. As a manufacturing method, avapor phase growth method such as plasma CVD or thermal CVD, orsputtering can be used. A droplet discharge method or a printing method(a method for forming a pattern, such as screen printing or offsetprinting) can also be used. A TOF film or an SOG film obtained by anapplication method can also be used.

First, the case where light is emitted to a light-transmitting substrate480 side, in other words, bottom emission is performed, will bedescribed with reference to FIG. 12A. In this case, a first electrode484, an electroluminescent layer 485, and a second electrode 486 aresequentially stacked in contact with a source/drain electrode layer 487so as to be electrically connected to the thin film transistor 481.Next, the case where light is emitted to the side opposite to thelight-transmitting substrate 460, in other words, top emission isperformed, will be described with reference to FIG. 12B. The thin filmtransistor 461 can be formed in a similar manner to the above describedthin film transistor except that it does not have a channel protectivelayer and parts of the n-type semiconductor layer, thelight-transmitting substance, and the semiconductor layer are removed byetching using the source/drain electrode layer as a mask. Thus, withrespect to the channel etch type thin film transistor 461, parts of thephotocatalyst and the low wettability substance used for controllablepattern formation are removed. As to the channel protective thin filmtransistor 481, in this embodiment mode, the photocatalyst and the lowwettability substance over the channel protective layer are not removed;however, they may be removed even in the case of the channel protectivetype. In addition, only the low wettability substance may be removed.

A source/drain electrode layer 462 that is electrically connected to thethin film transistor 461, a first electrode layer 463, anelectroluminescent layer 464, a second electrode layer 465 are stackedin order. With the above structure, even if the first electrode layer463 transmits light, the light is reflected by the source/drainelectrode layer 462, and the light is emitted to the side opposite tothe light-transmitting substrate 460. In this structure, the firstelectrode layer 463 is not required to use a light-transmittingmaterial. Finally, the case where light is emitted from both thelight-transmitting substrate side and the opposite side thereto, that isthe case where dual emission is carried out, will be described withreference to FIG. 12C. The thin film transistor 471 is a channelprotective thin film transistor the same as the thin film transistor481. So, it can be formed like the thin film transistor 481. Asource/drain electrode layer 477 that is electrically connected to thethin film transistor 471, a first electrode layer 472, anelectroluminescent layer 473, a second electrode layer 474 are stackedin order. In this occasion, when both the electrode layer 472 and thesecond electrode layer 474 are formed from materials that transmit lightor formed thin enough to transmit light, dual emission is realized.

Modes of a light emitting element which can be used in this embodimentmode is shown in FIGS. 30A to 30D. The light emitting element has astructure in which an electroluminescent layer 860 is interposed betweena first electrode layer 870 and a second electrode layer 850. Thematerials of the first electrode layer and the second electrode layerare required to be selected considering the work functions. The firstelectrode layer and the second electrode layer can be either an anode ora cathode depending on the pixel structure. In this embodiment mode, adriving TFT has n-channel conductivity, so that it is preferable thatthe first electrode layer serves as a cathode and the second electrodelayer serves as an anode. In the case where the driving TFT hasp-channel conductivity, the first electrode layer may be used as ananode and the second electrode layer may be used as a cathode.

FIGS. 30A and 30B show the case where the first electrode layer 870 isan anode and the second electrode layer 850 is a cathode. Theelectroluminescent layer 860 preferably has a structure in which an HIL(hole injection layer), HTL (hole transport layer) 804, EML (lightemitting layer) 803, ETL (electron transport layer), EIL (electroninjection layer) 802, and a second electrode layer 850 are stacked inorder from the first electrode layer 870 side. FIG. 30A shows astructure in which light is emitted from the first electrode layer 780side which is constituted by an electrode layer having alight-transmitting conductive oxide material, and the second electrodelayer has a structure in which an electrode layer 801 containing analkali metal or an alkaline earth metal such as LiF or MgAg and anelectrode layer 800 made of a metal material such as aluminum arestacked in order from the light emitting layer 860 side. FIG. 30B showsa structure in which the first electrode layer is constituted by anelectrode layer 807 made of a metal such as aluminum or titanium, or ametal material containing such metal and nitrogen of concentration instoichiometric proportion or less, and the second electrode layer 806made of a conductive oxide material containing silicon oxide in aconcentration of 1 to 15 atomic %. The second electrode layer isconstituted by an electrode layer 801 containing an alkali metal or analkaline earth metal such as LiF or MgAg and an electrode layer 800 madeof a metal material such as aluminum from the electroluminescent layer860 side; each layer is formed to a thickness of 100 nm or less; thus,the light can be emitted from the second electrode layer 850.

FIGS. 30C and 30D show the case where the first electrode layer 870 is acathode and the second electrode layer 850 is an anode. Theelectroluminescent layer 860 preferably has a structure in which an EIL(electron injection layer) and an ETL (electron transport layer) 802, anEML (light emitting layer) 803, an HTL (hole transport layer) and HIL(hole injection layer) 804, and the second electrode layer 850 which isan anode are stacked in order from the cathode side. FIG. 30C shows astructure in which light is emitted from the first electrode layer 870.The first electrode layer 870 is constituted by an electrode layer 801containing an alkali metal or an alkaline earth metal such as LiF orMgAg and an electrode layer 800 made of a metal material such asaluminum from the electroluminescent layer 860 side; each layer isformed to a thickness of 100 nm or less to transmit light; thus, thelight can be emitted through the first electrode layer 870. The secondelectrode layer is constituted by the second electrode layer 806 made ofa conductive oxide material containing silicon oxide in a concentrationof 1 to 15 atomic % and an electrode layer 807 made of a metal such asaluminum or titanium, or a metal material containing such metal andnitrogen of concentration in stoichiometric proportion or less, from theelectroluminescent layer 860 side. FIG. 30D shows a structure in whichlight is emitted from the second electrode layer 850. The firstelectrode layer 870 is constituted by an electrode layer 801 containingan alkali metal or an alkaline earth metal such as LiF or MgAg and anelectrode layer 800 made of a metal material such as aluminum from theelectroluminescent layer 860 side; the first electrode layer 870 isformed thick enough to reflect the light produced in theelectroluminescent layer 860. The second electrode layer 850 isconstituted by an electrode layer 805 made of a light-transmittingconductive oxide material. The electroluminescent layer may have asingle layer structure or a mixed structure other than a layeredstructure.

As the electroluminescent layer, materials each displays luminescence ofred (R), green (G), and blue (B) are selectively formed by anevaporation method using an evaporation mask or the like for each. Thematerials (low molecular weight materials or high molecular weightmaterials or the like) each displays luminescence of red (R), green (G),and blue (B) can be formed by a droplet discharge method in the samemanner as a color filter. This case is preferable since RGB can beseparately colored without using a mask.

In the case of the above top emission type, when ITSO or ITSO havinglight-transmitting properties are used for the second electrode layer,BzOS—Li in which Li is added to benzoxazole derivatives (BzOS) or thelike can be used. Alq₃ doped with a dopant corresponding to respectiveluminescent colors of R, G, and B (DCM or the like for R, and DMQD orthe like for G) may be used for the EML, for example.

Note that the electroluminescent layer is not limited to theabove-mentioned material. For example, hole injection properties can beenhanced by co-evaporating an oxide such as molybdenum oxide (MoO_(X):X=2 to 3) and α-NPD or rubrene instead of using CuPc or PEDOT. Anorganic material (including a low molecular weight material or a highmolecular weight material) or a composite material of an organicmaterial and an inorganic material can be used as the material of theelectroluminescent layer. A material forming a light emitting elementwill be described below in detail.

As a substance having high electron transport properties among chargeinjection transport materials, for example, a metal complex having aquinoline skeleton or a benzoquinoline skeleton such astris(8-quinolinolato)aluminum (Alq₃),tris(5-methyl-8-quinolinolato)aluminum (Almq₃),bis(10-hydroxybenzo[h]-quinolinato)beryllium (BeBq₂),bis(2-methyl-8-quinolinolato)-4-phenylphenolato-aluminum (BAlq), and thelike can be given. As a substance having high hole transport properties,for example, an aromatic amine compound (in other words, a compoundhaving the bond of benzene ring-nitrogen) such as4,4′-bis[N-(1-naphthyl)-N-phenyl-amino]-biphenyl (α-NPD),4,4′-bis[N-(3-methylphenyl)-N-phenyl-amino]-biphenyl (TPD),4,4′,4″-tris(N,N-diphenyl-amino)-triphenylamine (TDATA), or4,4′,4″-tris[N-(3-methylphenyl)-N-phenyl-amino]-triphenylamine (MTDATA)can be used.

As a substance having high electron injection properties among chargeinjection transport materials, a compound of an alkali metal or analkaline earth metal such as lithium fluoride (LiF), cesium fluoride(CsF), or calcium fluoride (CaF₂) can be given. In addition to this, itmay be a compound of a substance having high electron transportproperties such as Alq₃ and an alkaline earth metal such as magnesium(Mg).

As a substance having high hole injection properties among chargeinjection transport materials, for example, metal oxide such asmolybdenum oxide (MoO_(x)), vanadium oxide (VO_(x)), a ruthenium oxide(RuO_(x)), tungsten oxide (WO_(x)), manganese oxide (MnOx) are given. Inaddition, a phthalocyanine compound such as phthalocyanine (H₂Pc) orcopper phthalocyanine (CuPC) can be given.

The light emitting layer may have a structure to perform color displayby providing each pixel with light emitting layers having differentemission wavelength ranges. Typically, a light emitting layercorresponding to color of R (red), G (green), and B (blue) is formed. Onthis occasion, color purity can be improved and a pixel portion can beprevented from having a mirror surface (reflection) by providing thelight emitting side of the pixel with a filter which transmits light ofan emission wavelength range. By providing a filter, a circularlypolarizing plate or the like that is conventionally required can beomitted, and further, the loss of light emitted from the light emittinglayer can be eliminated. Further, change in hue, which occurs when apixel portion (display screen) is obliquely seen, can be reduced.

Various materials can be used for a light emitting material. As a lowmolecular weight organic light emitting material,4-dicyanomethylene-2-methyl-6-[2-(1,1,7,7-tetramethyljulolidyl-9-ethenyl]-4H-pyran;(DCJT);4-dicyanomethylene-2-t-butyl-6-(1,1,7,7-tetramethyljulolidine-9-ethenyl)]-4H-pyran(DPA); periflanthene;2,5-dicyano-1,4-bis[2-(10-methoxy-1,1,7,7-tetramethyljulolidine-9-yl)ethenyl]benzene;N,N′-dimethylquinacridon (DMQd); coumarin 6; coumarin 545T;tris(8-quinolinolato)aluminum (Alq₃); 9.9′-bianthryl;9,10-diphenylanthracene (DPA); 9,10-bis(2-naphthyl)anthracene (DNA); andthe like can be used. Another substance can also be used.

On the other hand, a high molecular weight organic light emittingmaterial is physically stronger than a low molecular weight material andis superior in durability of the element. In addition, a high molecularweight organic light emitting material can be formed by application, andtherefore, the element can be relatively easily manufactured. Thestructure of a light emitting element using a high molecular weightorganic light emitting material has basically the same structure as inthe case of using a low molecular weight organic light emittingmaterial, that is, a cathode, an organic light emitting layer, and ananode are stacked in order. However, a two-layer structure is employedin many cases when a light emitting layer using a high molecular weightorganic light emitting material is formed. This is because it isdifficult to form such a layered structure as in the case of using a lowmolecular weight organic light emitting material. Specifically, thelight emitting element using a high molecular weight organic lightemitting material has a structure of a cathode, a light emitting layer,a hole transport layer, and an anode in order.

The emission color is determined depending on a material forming a lightemitting layer; therefore, a light emitting element which displaysdesired luminescence can be formed by selecting an appropriate materialfor the light emitting layer. As a high molecular weightelectroluminescent material which can be used for forming a lightemitting layer, a polyparaphenylene-vinylene-based material, apolyparaphenylene-based material, a polythiophene-based material, or apolyfluorene-based material can be used.

As the polyparaphenylene vinylene-based material, a derivative ofpoly(paraphenylenevinylene) [PPV], for example,poly(2,5-dialkoxy-1,4-phenylenevinylene) [RO-PPV];poly(2-(2′-ethyl-hexoxy)-5-methoxy-1,4-phenylenevinylene) [MEH-PPV];poly(2-(dialkoxyphenyl)-1,4-phenylenevinylene) [ROPh-PPV]; and the likecan be given. As the polyparaphenylene-based material, a derivative ofpolyparaphenylene [PPP], for example, poly(2,5-dialkoxy-1,4-phenylene)[RO-PPP]; poly(2,5-dihexoxy-1,4-phenylene); and the like can be given.As the polythiophene-based msterial, a derivative of a derivative ofpolythiophene [PT], for example, poly(3-alkylthiophene) [PAT];poly(3-hexylthiophen) [PHT]; poly(3-cyclohexylthiophen) [PCHT];poly(3-cyclohexyl-4-methylthiophene) [PCHMT];poly(3,4-dicyclohexylthiophene) [PDCHT];poly[3-(4-octylphenyl)-thiophene] [POPT]; poly[3-(4-octylphenyl)-2,2bithiophene] [PTOPT]; and the like can be given. As thepolyfluorene-based material, a derivative of polyfluorene [PF], forexample, poly(9,9-dialkylfluorene) [PDAF]; poly(9,9-dioctylfluorene)[PDOF]; and the like can be given.

When a high molecular weight organic light emitting material having holetransport properties is interposed between an anode and a high molecularweight organic light emitting material having light emitting properties,hole injection properties from the anode can be enhanced. Generally, thehigh molecular weight organic light emitting material having holetransport properties which is dissolved in water along with an acceptormaterial is applied by spin coating or the like. In addition, the highmolecular weight light emitting material having hole injectionproperties is insoluble in an organic solvent; therefore, it can beformed over the above-mentioned high molecular weight organic lightemitting material having light emitting properties. As the highmolecular weight organic light emitting material having holetransportablity, a mixture of PEDOT and camphor-10-sulfonic acid (CSA)that serves as an acceptor material, a mixture of polyaniline [PANI] andpolystyrene sulfonic acid [PSS] that serves as an acceptor material, orthe like can be used.

The light emitting layer can be made to emit single color or whitelight. When a white light emitting material is used, color display canbe made possible by applying a structure in which a filter (a coloringlayer) which transmits light having a specific wavelength on the lightemitting side of a pixel is provided.

In order to form a light emitting layer that emits white light, forexample, Alq₃, Alq₃ partly doped with Nile red that is a red lightemitting pigment, p-EtTAZ, TPD (aromatic diamine) are laminatedsequentially by a vapor deposition method to obtain white light. In thecase that the light emitting layer is formed by an application methodusing spin coating, the layer formed by spin coating is preferably bakedby vacuum heating. For example, an aqueous solution of poly(ethylenedioxythiophene)/poly(styrene sulfonic acid) solution (PEDOT/PSS) may beentirely applied and baked to form a film that functions as a holeinjection layer. Then, a polyvinyl carbazole (PVK) solution doped with aluminescent center pigment (1,1,4,4-tetraphenyl-1,3-butadiene (TPB);4-dicyanomethylene-2-methyl-6-(p-dimethylamino-styryl)-4H-pyran (DCM1);Nile red; coumarin 6; or the like) may be entirely applied and baked toform a film that functions as a light emitting layer.

The light emitting layer may be formed to be a single layer. Forexample, a 1,3,4-oxadiazole derivative (PBD) having electron transportproperties may be dispersed in polyvinyl carbazole (PVK) having holetransporatbility. Further, white light emission can be obtained bydispersing PBD of 30 wt % as an electron transporting agent anddispersing an appropriate amount of four kinds of pigments (TPB,coumarin 6, DCM1, and Nile red). In addition to the light emittingelement from which white light emission can be obtained as shown here, alight emitting element which can provide red light emission, green lightemission, or blue light emission can be manufactured by appropriatelyselecting materials of the light emitting layer.

When a high molecular weight organic light emitting material having holetransport properties is formed by being interposed between an anode anda high molecular weight organic light emitting material having lightemitting properties, hole injection properties from the anode can beenhanced. Generally, the high molecular weight light emitting materialhaving hole transport properties which is dissolved in water along withan acceptor material is applied by spin coating or the like. Inaddition, the a high molecular weight light emitting material havinghole transport properties is insoluble in an organic solvent; therefore,it can be laminated over the above-mentioned organic light emittingmaterial having light emitting properties. As the high molecular weightorganic light emitting material having hole transport properties, amixture of PEDOT and camphor-10-sulfonic acid (CSA) that functions as anacceptor material, a mixture of polyaniline [PANI] and polystyrenesulfonic acid [PSS] that functions as an acceptor material, and the likecan be given.

Further, a triplet light emitting material containing a metal complex orthe like as well as a singlet light emitting material may be used forthe light emitting layer. For example, among pixels emitting red, green,and blue light, a pixel emitting red light whose luminance is reduced byhalf in a relatively short time is formed of a triplet light emittingmaterial and the rest are formed of a singlet let light emittingmaterial. A triplet light emitting material has a feature that thematerial has a good luminous efficiency and consumes less power toobtain the same luminance. When a triplet light emitting material isused for a red pixel, only small amount of current needs to be suppliedto a light emitting element. Thus, reliability can be improved. A pixelemitting red light and a pixel emitting green light may be formed of atriplet light emitting material and a pixel emitting blue light may beformed of a singlet light emitting material to achieve low powerconsumption. Low power consumption can be further achieved by forming alight emitting element which emits green light that has high visibilitywith a triplet light emitting material.

A metal complex used as a dopant is an example of a triplet lightemitting material, and a metal complex having platinum that is a thirdtransition series element as a central metal, a metal complex havingiridium as a central metal, and the like are known. A triplet lightemitting material is not limited to the compounds. A compound having theabove described structure and an element belonging to any of the Groups8 to 10 of the periodic table as a central metal can also be used.

The above described materials for forming the light emitting layer arejust examples. A light emitting element can be formed by appropriatelystacking functional layers such as a hole injection transport layer, ahole transport layer, an electron injection transport layer, an electrontransport layer, a light emitting layer, an electron blocking layer, anda hole blocking layer. Further, a mixed layer or a mixed junction may beformed by combining these layers. The layer structure of the lightemitting layer can be varied. Instead of providing a specific electroninjection region or light emitting region, modification such asproviding an electrode for the purpose or providing a dispersed lightemitting material is acceptable as long as it does not deviate from thescope of the present invention.

A light emitting element formed with the above described materials emitslight by being forward biased. A pixel of a display device formed with alight emitting element can be driven by a simple matrix mode or anactive matrix mode. In any event, each pixel emits light by applying aforward bias thereto at a specific timing; however, the pixel is in anon-light-emitting state for a certain period. Reliability of a lightemitting element can be improved by applying a reverse bias at thenon-light-emitting time. In a light emitting element, there is adeterioration mode in which emission intensity is decreased underspecific driving conditions or a deterioration mode in which anon-light-emitting region is enlarged in the pixel and luminance isapparently decreased. However, progression of deterioration can beslowed down by alternating current driving where bias is applied forwardand reversely. Thus, reliability of a light emitting device can beimproved. Additionally, both of digital driving and analog driving canbe applied.

A color filter (coloring layer) may be formed over thelight-transmitting substrate 480 and sealing substrates formed over thesubstrates 460 and 470 although it is not shown in FIGS. 12A to 12C. Thecolor filter (coloring layer) can be formed by a droplet dischargemethod, and in this case, light irradiation treatment or the like can beapplied as the above-mentioned base pretreatment. According to thepresent invention, a color filter (coloring layer) can be formed to havea desired pattern with good control. With the use of a color filter(coloring layer), high-definition display can also be performed. This isbecause a broad peak can be modified to be sharp in light emissionspectrum of each RGB.

As described above, the case of forming a material displayingluminescence of R, G, and B is shown, however, full color display can beperformed by forming a material displaying a single color and combininga color filter and a color conversion layer. The color filter (coloringlayer) or the color conversion layer is formed over, for example, asecond substrate (a sealing substrate) and may be attached to asubstrate. As described above, any of the material indicating a plaincolor, the color filter (coloring layer), and the color conversion layercan be formed by a droplet discharge method.

Naturally, display may be performed in monochrome. For example, adisplay device having an area color type may be manufactured by usingsingle color emission. The area color type is suitable for a passivematrix type display area, and a characters and symbols can be mainlydisplayed.

In the above-mentioned structure, it is possible to use a low workfunction material as a cathode, for example, Ca, Al, CaF, MgAg, AlLi, orthe like is desirable. Any of a single layer type, a layered type, amixed type having no interface between layers can be used for theelectroluminescent layer. The electroluminescent layer may be formed bya singlet material, a triplet material, or a mixture of the materials;or a charge injection transport material and a light emitting materialincluding an organic compound or an inorganic compound, which includesone layer or plural layers of a low molecular weight organic compoundmaterial, a middle molecular weight organic compound (which means anorganic compound having no sublimation properties, and the number ofmolecules is 20 or less or the length of liked molecules is 10 μm orless), and a high molecular weight organic compound, which are definedby the number of molecules, and may be combined with an electroninjection transport inorganic compound or a hole injection transportinorganic compound. The first electrode layer 484 (FIG. 12A), the firstelectrode layer 463 (FIG. 12B), and the first electrode layer 472 (FIG.12C) are formed by using a transparent conductive film which transmitslight, and for example, a transparent conductive film in which zincoxide (ZnO) of 2% to 20% is mixed in indium oxide is used in addition toITO or ITSO. Plasma treatment or heat treatment in vacuum atmosphere maybe preferably performed before forming the first electrode 484, thefirst electrode 463, and the first electrode 472. The partition wall(also referred to as a bank) is formed by using a material containingsilicon, an organic material or a compound material. Additionally, aporous film may be used. However, when a photosensitive material or anon-photosensitive material such as acrylic or polyimide is used toform, the side face thereof has a shape in which a radius curvaturechanges continuously, and an upper layer thin film is formed withoutdisconnection due to a step; therefore, it is preferable. Thisembodiment mode can be freely combined with the above-mentionedembodiment modes.

EMBODIMENT MODE 5

In a display panel manufactured according to Embodiment Modes 2 to 4,asshown in FIG. 14B, a scan line driver circuit can be formed over asubstrate 3700 by forming a semiconductor layer with a SAS.

FIG. 25 shows a block diagram of the scan line driver circuit includingn-channel TFTs using a SAS in which electric field effect mobility offrom 1 cm² V·sec to 15 cm²/V·sec is obtained.

In FIG. 25, a block 500 corresponds to a pulse output circuit outputtinga sampling pulse for one stage and a shift register includes n pulseoutputting circuits. Reference numeral 901 denotes a buffer circuit andconnected to a pixel 902.

FIG. 26 shows a specific structure of the block 500 which is a pulseoutput circuit, and the pulse output circuit includes n-channel TFTs 601to 613. The size of the TFTs may be decided in consideration of theoperation characteristics of the n-channel TFTs using a SAS. Forexample, when a channel length shall be 8 μm, the channel width can beset from 10 μm to 80 μm.

In addition, FIG. 27 shows a specific structure of the buffer circuit901. The buffer circuit includes n-channel TFTs 620 to 635 in the samemanner. At this time, the size of the TFTs may be decided inconsideration of the operation characteristics of the n-channel TFTsusing a SAS. For example, when a channel length shall be 10 μm, thechannel width can be set from 10 μm to 1800 μm. According to the presentinvention, a pattern can be formed to have a desired shape with goodcontrol; therefore, a fine wiring like this having a channel width of 10μm can be stably formed without a fault such as a short circuit.

It is necessary to connect the TFTs with one another with wirings torealize such circuits, and FIG. 16 shows a structural example of wiringsof the case. As well as in Embodiment Mode 2, FIG. 16 shows a state inwhich a gate electrode layer 103, a gate insulating layer 106 (alaminate of three layers including an insulating layer containingsilicon nitride, an insulating layer containing silicon oxide, and aninsulating layer containing silicon nitride in this embodiment mode), asemiconductor layer 107 formed of an organic semiconductor, andsource/drain electrode layers 111 and 112 are formed. In this embodimentmode, a photocatalyst 101 and a layer having low wettability substanceare formed over the gate insulating layer 106; formation region of thesource/drain electrode layers 111 and 112 are modified by beingirradiated with light from the light-transmitting 100 side using thegate electrode layer 103 as a mask. In this embodiment mode, themodification is formed to control wettability. The photocatalyst 101 isactivated by light irradiation, and a surface of a low wettabilitysubstance 155 a is modified by the energy. Accordingly, a lowwettability region 150, and high wettability regions 151 a and 151 bwhich have relatively different wettability are formed. A compositioncontaining a conductive material is discharged to the high wettabilityregions 151 a and 151 b, so that the source/drain electrode layers 111and 112 can be formed with good control.

In Embodiment Mode 2, since the semiconductor layer 107 is formed by adroplet discharge method, the low wettability substance formed over thelow wettability region 150 is also irradiated with light to enhance thewettability. However, in this embodiment mode, the semiconductor layer107 is formed by vacuum deposition using pentacene which is an organicsemiconductor; therefore, the step of controlling the wettability of thelow wettability region 150 is not required. Further, the semiconductorlayer 107 may be formed by a droplet discharge method or the like usingthe composition in liquid form if the surface to be provided with acomposition is wettable enough with the composition. In this embodimentmode, the low wettability region 150, the high wettability region 151 a,and the high wettability region 151 b are named for conveniencedepending on relative wettability difference with the compositioncontaining a conductive material for forming the source/drain electrodelayer. Accordingly, even when the formation region of the semiconductorlayer displays low wettability with the composition containing aconductive material for the source/drain electrode layer, it is possiblethat the formation region does not have low wettability with thecomposition for forming the semiconductor layer 107. In such a case, thestep of controlling the wettability of the formation region of thesemiconductor layer 107 is not required.

Connection wiring layers 160, 161, and 162 are formed over a substrate100 through the same steps as the gate electrode layer 104. Parts of agate insulating layer are etched so that the connection wiring layers160, 161, and 162 are exposed, and TFTs are appropriately connected withthe use of the source/drain electrode layers 111 and 112, and aconnection wiring layer 163 formed in the same step; thus, a variety ofcircuits can be realized.

EMBODIMENT MODE 6

A mode of mounting a driver circuit on a display panel manufacturedaccording to Embodiment Modes 2 to 5 will be described.

First, a display device employing a COG method is described withreference to FIG. 15A. A pixel portion 2701 having pixel 2702 fordisplaying information on characters, images or the like is providedover a substrate 2700. A substrate provided with a plurality of drivercircuits is divided into rectangles, and the divided driver circuits(hereinafter also referred to as a driver IC) 2751 are mounted on thesubstrate 2700. FIG. 15A shows a mode of mounting a plurality of driverICs 2751 and FPCs 2750 on the end of the driver ICs 2751. In addition,the divided size may be made almost the same as the length of a side ofa pixel portion on a signal line side, and a tape may be mounted on theend of a single driver IC.

A TAB method may be adopted. In that case, a plurality of tapes may beattached and driver ICs may be mounted on the tape as shown in FIG. 15B.Similarly to the case of a COG method, a singular driver IC may bemounted on a singular tape. In that case, a metal piece or the like forfixing the driver IC may be attached together in terms of the matter ofintensity.

A plurality of the driver ICs to be mounted on a display panel ispreferably formed over a rectangular substrate having a side of from 300mm to 1000 mm or more in terms of improving production efficiency.

In other words, a plurality of circuit patterns including a drivercircuit portion and an input-output terminal as a unit is formed overthe substrate, and may be lastly divided to be used. In consideration ofa side length of the pixel portion and the pixel pitch, the driver ICmay be formed to be a rectangle having a long side (length) of 15 mm to80 mm and a short side of from 1 mm to 6 mm. Alternatively, the driverIC may be formed to have the long side length of a side length of thepixel portion, or the long side length of adding the pixel portion to aside length of each driver circuit.

An advantage of the external dimension over an IC chip of a driver IC isthe length of the long side. When a driver IC having a long side of from15 mm to 80 mm is used, the number of driver ICs necessary for mountingin accordance with the pixel portion is less than that in the case ofusing an IC chip. Therefore, a yield in manufacturing can be improved.When a driver IC is formed over a glass substrate, production efficiencyis not impaired, without limitation due to the shape of a substrate usedas a mother body. This is a great advantage compared with the case oftaking IC chips out of a circular silicon wafer.

When a scan line driver circuit 3702 is integrally formed over thesubstrate as shown in FIG. 14B, the driver IC provided with a signalline driver circuit is mounted on a region outside the pixel portion3701. The driver IC is a signal line driver circuit. In order to form apixel portion corresponding to RGB full color, 3072 signal lines arerequired for an XGA class and 4800 signal lines are required for a UXGAclass. The signal lines formed in such a number are divided into severalblocks on an end of the pixel portion 3701 to form lead lines. Thesignal lines are gathered corresponding to the pitches of outputterminals of the driver ICs.

The driver IC is preferably made of a crystalline semiconductor formedover a substrate. The crystalline semiconductor is preferably formed bybeing irradiated with continuous wave laser light. Therefore, acontinuous wave solid-state laser or gas laser is used as an oscillatorfor generating the laser light. There are few crystal defects when acontinuous wave laser is used, and as a result, a transistor can beformed by using a polycrystalline semiconductor layer with a large grainsize. In addition, high-speed driving is possible since mobility orresponse speed is favorable, and it is possible to further improve anoperating frequency of an element than that of the conventional element.Therefore, high reliability can be obtained since there are fewcharacteristics variations. Note that the channel-length direction of atransistor and a scanning direction of laser light may be directed inthe same direction to further improve an operating frequency. This isbecause the highest mobility can be obtained when a channel lengthdirection of a transistor and a scanning direction of laser light withrespect to a substrate are almost parallel (preferably, from −30° to30°) in a step of laser crystallization by a continuous wave laser. Thechannel length direction coincides with the flowing direction of acurrent, in other words, a direction in which an electric charge movesin a channel formation region. The thus manufactured transistor has anactive layer including a polycrystalline semiconductor layer in which acrystal grain is extended in the channel direction, and this means thata crystal grain boundary is formed almost along the channel direction.

In order to perform laser crystallization, it is preferable toextensively focus the laser light, and the beam spot thereof preferablyhas the same width as that of a short side of the driver ICs,approximately from 1 mm to 3 mm. In addition, in order to secure anenough and effective energy density for an object to be irradiated, anirradiation region of the laser light preferably has a linear shape. Asused herein, the term “linear” refers to not a line in a strict sensebut a rectangle or an oblong with a large aspect ratio. For example, thelinear shape refers to a rectangle or an oblong with an aspect ratio of2 or more (preferably from 10 to 10000). Thus, it is possible to providea method for manufacturing a display device in which productivity isimproved by making a beam spot width of the laser light and that of ashort side of the driver ICs to have the same length.

As shown in FIGS. 15A and 15B, driver ICs may be mounted as both a scanline driver circuit and a signal line driver circuit. In this case, itis preferable to differentiate specifications of the scan line drivercircuit and the signal line driver circuit.

In the pixel portion, the signal line and the scan line intersect toform a matrix and a transistor is arranged in accordance with eachintersection. A TFT having an amorphous semiconductor or a semiamorphoussemiconductor as a channel portion is used as the transistor arranged inthe pixel portion in the present invention. The amorphous semiconductoris formed by a method such as plasma CVD or sputtering. It is possibleto form the semiamorphous semiconductor at temperatures of 300° C. orless by plasma CVD. A film thickness necessary to form a transistor isformed in a short time even in the case of a non-alkaline glasssubstrate of an external size of, for example, 550 mm×650 mm. Thefeature of such a manufacturing technique is effective in manufacturinga large-area display device. In addition, a semiamorphous TFT can obtainfield effect mobility of from 2 cm²/V·sec to 10 cm²V·sec by forming achannel formation region of a SAS. When the present invention isapplied, a fine wiring having a short channel width can be stably formedwithout a fault such as a short circuit since a pattern can be formed tohave a desired shape with good control. Accordingly, TFT having electriccharacteristics required to operate a pixel sufficiently. Therefore,this TFT can be used as a switching element of pixels and as an elementconstituting the scan line driver circuit. Thus, a display panel inwhich system-on-panel is realized can be manufactured.

The scan line driver circuit is also integrally formed over thesubstrate by using a TFT having a semiconductor layer formed of asemiamorphous semiconductor (SAS). In the case of using a TFT having asemiconductor layer formed of an amorphous semiconductor (AS), a driverIC may be mounted as both the scan line driver circuit and the signalline driver circuit.

In that case, it is preferable to differentiate specifications of thedriver ICs to be used on the scan line and on the signal line. Forexample, a transistor constituting the scan line side driver ICs isrequired to withstand a voltage of approximately 30 V, however, a drivefrequency is 100 kHz or less and high-speed operation is notcomparatively required. Therefore, it is preferable to set achannel-length (L) of the transistor included in the scan line driversufficiently long. On the other hand, a transistor of the signal linedriver ICs is required to withstand a voltage of only approximately 12V, however, a drive frequency is around 65 MHz at 3 V and high-speedoperation is required. Therefore, it is preferable to set achannel-length or the like of the transistor included in a driver with amicron rule. According to the present invention, a fine pattern can beformed with good control; therefore, the present invention cancorrespond to such a micron rule sufficiently.

A method for mounting a driver IC is not particular limited, and a knownmethod such as a COG method, a wire bonding method, or a TAB method canbe employed.

The heights of the driver IC and the counter substrate can be madealmost the same by forming the driver IC to have the same thickness asthat of the counter substrate, which contributes to thinning a displaydevice as a whole. When both substrates are formed of the same material,thermal stress is not generated and characteristics of a circuitincluding a TFT are not harmed even when temperature change is generatedin the display device. Furthermore, the number of driver ICs to bemounted on one pixel portion can be reduced by mounting a longer driverIC than an IC chip as a driver circuit as described in this embodimentmode.

As described above, a driver circuit can be incorporated in a displaypanel.

EMBODIMENT MODE 7

A structure of a pixel of a display panel shown in this embodiment isdescribed with reference to equivalent circuit diagrams shown in FIGS.17A to 17F.

In a pixel shown in FIG. 17A, a signal line 410 and power supply lines411 to 413 are arranged in columns, and a scan line 414 is arranged in arow. The pixel also includes a switching TFT 401, a driving TFT 403, acurrent controlling TFT 404, a capacitor element 402, and alight-emitting element 405.

A pixel shown in FIG. 17C has the same structure as the one shown inFIG. 17A, except that a gate electrode of the driving TFT 403 isconnected to the power supply line 415 arranged in a row. Both pixels inFIGS. 17A and 17C show the same equivalent circuit diagrams. However,each power supply line is formed of conductive layers in differentlayers in between the cases where the power supply line 412 is arrangedin a column (FIG. 17A) and where the power supply line 415 is arrangedin a row (FIG. 17C). The two pixels are each shown in FIGS. 17A and 17Cin order to show that layers in which a wiring connected to the gateelectrode of the driving TFT 403 is formed are different in betweenFIGS. 17A and 17C.

In both FIGS. 17A and 17C, the TFTs 403 and 404 are connected in seriesin the pixel, and the ratio of the channel length L₃/the channel widthW₃ of the TFT 403 to the channel length L₄/the channel width W₄ of theTFT 404 is set as L₃/W₃:L₄/W₄=5 to 6000:1. For example, when L₃, W₃, L₄,and W₄ are 500 μm, 3 μm, 3 μm, and 100 μm, respectively. According tothe present invention, such a fine wiring having 3 μm W₃ can be stablyformed without a fault such as a short circuit since a pattern can beformed to have a desired shape with good control. Hence, a TFT havingelectric characteristics required for sufficiently operating such pixelsshown in FIGS. 17A and 17C can be formed. As a result, a highly reliabledisplay panel superior in display capability can be manufactured.

The TFT 403 is operated in a saturation region and controls the amountof current flowing in the light emitting element 405, whereas the TFT404 is operated in a linear region and controls a current supplied tothe light emitting element 405. The TFTs 403 and 404 preferably have thesame conductivity in view of the manufacturing process. For the drivingTFT 403, a depletion type TFT may be used instead of an enhancement typeTFT. According to the present invention having the above structure,slight variations in V_(GS) of the TFT 404 does not affect the amount ofcurrent flowing in the light emitting element 405, since the currentcontrolling TFT 404 is operated in a linear region. That is, the amountof current flowing in the light emitting element 405 is determined bythe TFT 403 operated in a saturation region. Accordingly, it is possibleto provide a display device in which image quality is improved byimproving variations in luminance of the light emitting element due tothe variation of the TFT properties.

The TFTs 401 of pixels shown in FIGS. 17A to 17D controls a video signalinput to the pixel. When the switching TFT 401 is turned ON and a videosignal is input to the pixel, the video signal is held in the capacitorelement 402. Although the pixel includes the capacitor element 402 inFIGS. 17A to 17D, the present invention is not limited thereto. When agate capacitance or the like can serve as a capacitor for holding avideo signal, the capacitor element 402 is not necessarily provided.

The light emitting element 405 has a structure in which anelectroluminescent layer is sandwiched between a pair of electrodes. Apixel electrode and a counter electrode (an anode and a cathode) have apotential difference therebetween so that a forward bias voltage isapplied. The electroluminescent layer is formed of wide range ofmaterials such as an organic material, an inorganic material. Theluminescence in the electroluminescent layer includes luminescence thatis generated when an excited singlet state returns to a ground state(fluorescence) and luminescence that is generated when an exited tripletstate returns to a ground state (phosphorescence).

A pixel shown in FIG. 17B has the same structure as the one shown inFIG. 17A, except that a TFT 406 and a scan line 416 are added.Similarly, a pixel shown in FIG. 17D has the same structure as the oneshown in FIG. 17C, except that a TFT 406 and a scan line 416 are added.

The TFT 406 is controlled to be ON/OFF by the added scan line 415. Whenthe TFT 406 is turned ON, charges held in the capacitor element 402 aredischarged, thereby turning the TFT 404 OFF. That is, supply of acurrent to the light emitting element 405 can be forcibly stopped byproviding the TFT 406. Therefore, a lighting period can startsimultaneously with or shortly after a writing period starts beforesignals are written into all the pixels by adopting the structures shownin FIGS. 17B and 17D, thus, the duty ratio can be improved.

In a pixel shown in FIG. 17E, a signal line 450 and power supply lines451 and 452 are arranged in columns, and a scan line 453 is arranged ina row. The pixel further includes a switching TFT 441, a driving TFT443, a capacitor element 442, and a light emitting element 444. A pixelshown in FIG. 17F has the same structure as the one shown in FIG. 17E,except that a TFT 445 and a scan line 454 are added. It is to be notedthat the structure of FIG. 17F also allows a duty ratio to be improvedby providing the TFT 445.

As described above, according to the present invention, a pattern of awiring or the like can be stably formed with good control without abreak. Therefore, a TFT can be provided with high electriccharacteristics and reliability, and the present invention cansatisfactorily be used for an applied technique for improving displaycapacity of a pixel in accordance with the intended use.

EMBODIMENT MODE 8

One mode in which protective diodes are provided for a scan line inputterminal portion and a signal line input terminal portion is explainedwith reference to FIG. 24. TFTs 501 and 502, a capacitor 504, a lightemitting element 503, a gate line 506, and a power supply line 507 areprovided for a pixel 2702 in FIG. 24. This TFT has the same structure asthat in Embodiment Mode 2.

Protective diodes 261 and 262 are provided for the signal line inputterminal portion. These protective diodes are manufactured in the samestep as that of the TFT 260 and being operated as a diode by being eachconnected to a gate and one of a drain or a source. FIG. 23 shows anequivalent circuit diagram such as a top view shown in FIG. 24.

The protective diode 561 includes a gate electrode layer, asemiconductor layer, a wiring layer. The protective diode 562 has thesame structure. Common potential lines 554 and 555 connecting to thisprotective diode are formed in the same layer as that of the gateelectrode layer. Therefore, it is necessary to form a contact hole inthe gate insulating layer to electrically connect to the wiring layer.

A mask layer may be formed and etching-processed to form a contact holein the gate insulating layer. In this case, when etching-process atatmospheric pressure discharge is applied, electric discharging processcan be locally performed, and a mask layer is not necessarily formedover the entire surface.

A signal wiring layer is formed in the same layer as that of asource/drain wiring layer 505 in the TFT 501 and has a structure inwhich the signal wiring layer connected thereto is connected to thesource or drain side.

The input terminal portion of the scanning signal line side also has thesame structure. A protective diode 563 includes a gate electrode layer,a semiconductor layer, and a wiring layer. A protective diode 564 alsohas the same structure. Common potential lines 556 and 557 connected tothe protective diode are formed in the same layer as that of thesource/drain wiring layer. According to the present invention, theprotective diodes provided in an input stage can be formed at the sametime. Note that the position of depositing a protective diode is notlimited to this embodiment mode and can also be provided between adriver circuit and a pixel.

As described above, according to the present invention, a pattern of awiring or the like can be stably formed without generating a formationdefect with good control. Therefore, even when a wiring or the like iscomplex and formed densely by forming a protective circuit, a short orthe like due to the defect of installation at the time of formation isnot generated. Additionally, the present invention can correspond to aminiaturized or thinned device sufficiently since it is not necessary totake wide margin into consideration. As a result, a display devicehaving preferable electric characteristics and high reliability can bemanufactured.

EMBODIMENT MODE 9

FIG. 22 shows an example constituting an EL display module having a TFTsubstrate 2800 manufactured according to the present invention. A pixelportion including pixels is formed over the TFT substrate 2800.

In FIG. 22, a TFT which is the same as that formed in a pixel or aprotective circuit portion 2801 operated in the same manner as a diodeby being connected to a gate and one of a source or a drain of the TFTis provided between a driver circuit and the pixel which is outside ofthe pixel portion. A driver IC formed of a single crystal semiconductor,a stick driver IC formed of a polycrystalline semiconductor film over aglass substrate, or a driver circuit formed of a SAS is applied to adriver circuit 2809.

The TFT substrate 2800 is bonded to a sealing substrate 2820 byinterposing spacers 2806 a and 2806 b therebetween. The spacer ispreferably provided to keep the space between two substrates constantlyeven when a substrate is thin and an area of a pixel portion isenlarged. A space between the TFT substrate 2800 and the sealingsubstrate 2820 over light emitting elements 2804 and 2805 connected toTFTs 2802 and 2803, respectively may be filled with a light-transmittingresin material and solidified, or may be filled with anhydrous nitrogenor an inert gas.

FIG. 22 shows the case in which the light emitting elements 2804 and2805 have a structure of a top emission type and has a structure inwhich light is emitted in the direction of the arrow shown in thefigure. Multicolor display can be carried out in each pixel by havingdifferent luminescent colors of red, green, and blue. In addition, atthis time, color purity of the luminescence emitted outside can beenhanced by forming coloring layers 2807 a, 2807 b and 2807 ccorresponding to each color on the sealing substrate 2820 side.Moreover, the coloring layers 2807 a, 2807 b and 2807 c may be combinedby using the pixel as a white light emitting element.

The driver circuit 2809 which is an external circuit is connected to ascan line or signal line connection terminal provided over one end of anexternal circuit substrate 2811 through a wiring substrate 2810. Inaddition, a heat pipe 2813 and a heat sink 2812 may be provided to be incontact with or close to the TFT substrate 2800 to have a structureimproving a heat effect.

FIG. 22 shows the top emission type EL module, however, it may be abottom emission structure by changing the structure of the lightemitting element or the disposition of the external circuit substrate.Naturally, a dual emission structure in which light is emitted to bothsides of the top and bottom surfaces may be used. In the case of the topemission structure, the insulating layer which is to be a partition wallmay be colored to be used as a black matrix. This partition wall can beformed by a droplet discharge method or the like and it may be formed bymixing a black resin of a pigment material, carbon black, or the likeinto a resin material such as polyimide, or a lamination thereof may bealso used.

Additionally, in the TFT substrate 2800, a sealing structure may beformed by attaching a resin film to the side where the pixel portion isformed with the use of a sealant or an adhesive resin. In thisembodiment mode, glass sealing using a glass substrate is shown,however, various sealing methods such as resin sealing using a resin,plastic sealing using plastic, and film sealing using a film can beused. A gas barrier film which prevents moisture from penetrating ispreferably provided on the surface of a resin film. By applying a filmsealing structure, further thinner and lighter can be realized.

EMBODIMENT MODE 10

A television device can be completed by a display device formedaccording to the present invention. A display panel can be formed in anymanners as follows: as the structure shown in FIG. 14A, in the casewhere only a pixel portion is formed, and then a scan line drivercircuit and a signal line driver circuit are mounted by a TAB method asshown in FIG. 15B; as the structure shown in FIG. 14A, in the case whereonly a pixel portion is formed, and then a scan line driver circuit anda signal line driver circuit are mounted by a COG method as shown inFIG. 15A; a TFT is formed of a SAS, a pixel portion and a scan linedriver circuit are integrally formed over a substrate, and a signal linedriver circuit is separately mounted as a driver IC as shown in FIG.14B; and a pixel portion, a signal line driver circuit, and a scan linedriver circuit are integrally formed over the substrate as shown in FIG.14C; or the like.

Another structure of an external circuit includes a video signalamplifier circuit which amplifies a video signal received by a tuner; avideo signal processing circuit which converts the video signal outputtherefrom into a chrominance signal corresponding to each color of red,green, and blue; a control circuit which converts the video signal intoan input specification of a driver IC; and the like on inputting side ofthe video signal. The control circuit outputs the signal into the scanline side and the signal line side, respectively. In the case of digitaldriving, a signal division circuit may be provided on the signal lineside so as to have a structure in which an input digital signal isprovided by dividing into m-pieces.

Among a signal received from the tuner, an audio signal is transmittedto an audio signal amplifier circuit, and the output thereof is providedfor a speaker through an audio signal processing circuit. A controlcircuit receives control information on a receiving station (a receivingfrequency) or sound volume from an input portion and transmits thesignal to the tuner or the audio signal processing circuit.

FIG. 13 shows an example of a liquid crystal display module, and a TFT2600 and a counter substrate 2601 are fixed with a sealant 2602, with apixel portion 2603 and a liquid crystal layer 2604 interposedtherebetween to form a display region. Coloring layer 2605 is requiredin the case of performing a color display. In the case of an RGB method,coloring layers corresponding to red, green, and blue are provided foreach pixel. Polarizing plates 2606 and 2607, an optical film 2613 areprovided outside the TFT substrate 2600 and the counter substrate 2601.A light source includes a cold cathode tube 2610 and reflection plate2611, and a circuit substrate 2612 is connected to the TFT substrate2600 through a driver circuit 2608 and a flexible wiring substrate 2609and an external circuit such as a control circuit or a power supplycircuit is incorporated.

As shown in FIGS. 20A and 20B, a television device can be completed byincorporating a display module into a chassis 2001. An EL televisiondevice can be completed when an EL display module as in FIG. 22 is used,and a liquid crystal television device can be completed when a liquidcrystal module as in FIG. 13 is used. A main screen 2003 is formed byusing the display module, and a speaker portion 2009, operationswitches, and the like are provided as other attached equipments. Insuch a manner, the television device can be completed according to thepresent invention.

In addition, reflected light of light entered from exterior may beshielded by using a retardation film and a polarizing plate. FIG. 19 isa structure of a top emission type and an insulating layer 3605 which isto be a partition wall is colored to use as a black matrix. Thepartition wall can be formed by a droplet discharge method, and carbonblack or the like may be mixed into a resin material such as polyimide,and a lamination thereof may be also used. Depending on a dropletdischarge method, different materials may be discharged on the sameregion plural times to form the partition wall. In this embodiment mode,a black resin of a pigment is used. A λ/4 plate and a λ/2 plate may beused as retardation films 3603 and 3604 and may be designed to be ableto control light. As the structure, a TFT element substrate 2800, alight emitting element 2804, a sealing substrate (sealant) 2820, aretardation films (λ/4 and λ/2) 3603 and 3604, a polarizing plate 3602are sequentially laminated, in which light emitted from the lightemitting element is emitted outside of the polarizing plate side totransmit them. The retardation film or polarizing plate may be providedon a side where light is emitted or may be provided on the both sides inthe case of a dual emission type display device in which light isemitted from the both faces. In addition, an anti-reflective film 3601may be provided on the outer side of the polarizing plate. Accordingly,a higher definition and more accurate image can be displayed.

As shown in FIG. 20A, a display panel 2002 using a display element isincorporated into a chassis 2001. By using a receiver 2005, in additionto receiving general TV broadcast, information communication can also becarried out in one direction (from a transmitter to a receiver) or inthe both directions (between a transmitter and a receiver or betweenreceivers) by connecting to a communications network by a fixed line ora wireless through a modem 2004. The operation of the television devicecan be carried out by switches incorporated into the chassis or by aremote control device 2006, which is separated from the main body. Adisplay portion 2007 that displays information to be output may be alsoprovided for this remote control device.

In addition, in the television device, a structure displaying a channel,sound volume, or the like may be additionally provided by forming asub-screen 2008 of a second display panel in addition to the main screen2003. In this structure, the main screen 2003 is formed of an EL displaypanel superior in a viewing angle, and the sub-screen may be formed of aliquid crystal display panel capable of displaying the sub-screen withlow power consumption. In order to prioritize low power consumption, astructure in which the main screen 2003 is formed of a liquid crystaldisplay panel, the sub-screen is formed of an EL display panel, and thesub-screen is able to flash on and off may be also applied. According tothe present invention, a display device with high reliability can bemanufactured even by using many TFTs and electronic parts by using sucha large-sized substrate.

FIG. 20B shows a television device having a large-sized display portionof, for example, 20 inches to 80 inches, which includes a chassis 2010,a keyboard portion 2012 which is an operation portion, a display portion2011, a speaker portion 2013, and the like. The present invention isapplied to manufacturing the display portion 2011. FIG. 20B shows atelevision device having a curved display portion since a substancewhich is capable of curving is used for the display portion. Thus, atelevision device having a desired shape can be manufactured since theshape of the display portion can be freely designed.

Using the present invention enables to simplify the process.Accordingly, a display panel can be easily manufactured even when aglass substrate which is in and after the fifth generation having 1000mm or more on a side is used.

According to the present invention, a desired pattern can be formed withgood control, and the material loss and the cost can be reduced. Hence,a television device even with a large screen display portion can beformed with low cost by applying the present invention, and a defect isnot generated even when the television device is thinned and a wiring orthe like becomes precise. Accordingly, a high-performance and highlyreliable television device can be manufactured with a preferable yield.

Naturally, the present invention is not limited to the television deviceand it can be applied to various usages especially as the displaymediums having a large area such as an information display board at astation, an airport, or the like, or an advertisement display board onthe street as well as a monitor of a personal computer.

EMBODIMENT MODE 11

Various display devices can be manufactured by applying the presentinvention. In other words, the present invention can be applied tovarious electronic devices in which these display devices areincorporated into display portions.

The electronic devices include a camera such as a video camera or adigital camera, a projector, a head mounted display (a goggle typedisplay), a car navigation system, a car stereo, a personal computer, agame machine, a portable information terminal (a mobile computer, acellular phone, an electronic book, or the like), an image reproducingdevice provided with a recording medium (specifically a device that iscapable of playing a recording medium such as a Digital Versatile Disc(DVD) and that has a display device that can display the image) or thelike. FIGS. 21A to 21D show the examples thereof.

FIG. 21A shows a computer, which includes a main body 2101, a chassis2102, a display portion 2103, a keyboard 2104, an external connectionport 2105, a pointing mouse 2106 and the like. According to the presentinvention, a computer in which an image with high reliability and highresolution can be displayed can be completed even the computer isminiaturized and a wiring or the like becomes precise.

FIG. 21B shows an image reproducing device provided with a recordingmedium (specifically a DVD reproducing device), which includes a mainbody 2201, a chassis 2202, a display portion A 2203, a display portion B2204, a recording medium (such as a DVD) reading portion 2205, operationkeys 2206, a speaker portion 2207 and the like. The display portion A2203 mainly displays image information and the display portion B 2204mainly displays character information. According to the presentinvention, an image producing device in which an image with highreliability and high resolution can be displayed can be completed evenwhen the image reproducing device is miniaturized and a wiring or thelike becomes precise.

FIG. 21C shows a cellular phone, which includes a main body 2301, anaudio output portion 2302, an audio input portion 2303, a displayportion 2304, operation switches 2305, an antenna 2306, and the like.According to the present invention, a cellular phone in which an imagewith high reliability and high resolution can be displayed can becompleted even when the cellular phone is miniaturized and a wiring orthe like becomes precise.

FIG. 11D shows a video camera, which includes a main body 2401, adisplay portion 2402, a chassis 2403, an external connection port 2404,a remote control receiving portion 2405, an image receiving portion2406, a battery 2407, an audio input portion 2408, operation switches2409, eyepiece portion 2410, and the like. According to the presentinvention, a video camera in which an image with high reliability andhigh resolution can be displayed can be completed even when the videocamera is miniaturized and a wiring or the like becomes precise. Thisembodiment mode can be freely combined with the above-mentionedembodiment modes.

EMBODIMENT 1

In this embodiment, an effect of the present invention will be explainedbased on experimental results.

A glass substrate as a substrate, titanium oxide as a photocatalyst, andFAS as a low wettability substance are used. A TiCl₃ solution is appliedto the glass substrate and baked to form a titanium oxide layer, andthereafter FAS is formed thereover. The TiCl₃ solution is a solution inwhich TiCl₃ is dissolved in a dilute hydrochloric acid solution in aconcentration of 2% by weight. The baking is carried out in an oxygenatmosphere at 450° C. for 30 minutes. In addition, isopropyl alcohol isused for the solvent of FAS.

A sample in which only FAS is formed over the a glass substrate withouta titanium oxide layer for comparative examples and the above-mentionedsample according to the present invention are irradiated with light. Thelight irradiation is carried out through the glass substrate from theglass substrate side using a metal halide lamp as the light source;light with a wavelength of 300 nm to 400 nm is applied. The relationbetween the contact angle of water in the irradiated area and lightirradiation time is shown in FIG. 31.

In FIG. 31, the black squares correspond to the comparative examplewhich does not use the present invention, and the black rhombusescorrespond to the sample of this embodiment applying the presentinvention. The contact angle of water with the surface of the sample ofthe comparative example hardly changes from 94° before the irradiationand even after the light irradiation for 60 seconds, to 93° through thelight irradiation for 180 seconds; thus, the contact angle value hardlychanges. The energy of light with a wavelength of 200 nm or less isrequired to decompose the FAS that is a low wettability substance,however, the glass substrate absorbs the wavelength of 300 nm or less.Accordingly, FAS is irradiated with only light with a wavelength of 300nm or more; therefore, FAS is not decomposed. As can be seen from thevalue of the contact angle, the wettability of the surface of the sampleof the comparative example is not changed, and the surface is notmodified.

The contact angle of water with a surface of the sample provided with atitanium oxide layer as a photocatalyst under FAS is reduced from 108°before the irradiation, to 95° through light irradiation for 10 seconds,70° in 30 seconds, 25° in 60 seconds, and 7° in 90 seconds. FAS isnormally decomposed only with light having a wavelength of 200 nm orless; however, it is understood that FAS is decomposed with light havinga wavelength of around 300 nm to 400 nm due to the photocatalytic effectof titanium oxide according to the present invention. Thus, it is foundthat the wettability of the surface of the sample of this embodimentaccording to the present invention is improved by light irradiation, andthe surface is modified.

Since the modification capacity of a photocatalyst is improved byapplying the present invention, the range of options for light isincreased. Accordingly, the wavelength that is hardly absorbed by asubstance to be provided with an object can be applied, and lightirradiation for controllable surface modification treatment can becarried out. Further, the efficiency of light irradiation can beimproved, so that the treatment can be completed even though the lightitself has low energy. As a result, the apparatuses and steps aresimplified, thus, costs and time are reduced, and the productionefficiency can be improved.

1. A method for forming a pattern, comprising the steps of: forming amask over a light-transmitting substrate; forming a first regionincluding a photocatalyst over the light-transmitting substrate and themask; forming a material containing a fluorocarbon chain over thephotocatalyst; irradiating the photocatalyst and the material containingthe fluorocarbon chain with light through the light-transmittingsubstrate to modify a part of a surface of the material containing thefluorocarbon chain which is to be a second region; and discharging aconductive composition containing a pattern forming material to thesecond region to form a pattern, wherein the mask does not transmit thelight.
 2. A method according to claim 1, wherein titanium oxide is usedas the photocatalyst to form the first region.
 3. A method according toclaim 1, wherein a surface of the material containing the fluorocarbonchain is modified so that the second region has higher wettability withthe composition than the first region.
 4. A method for manufacturing athin film transistor, comprising the steps of: forming a firstconductive layer over a light-transmitting substrate; forming aninsulating layer over the light-transmitting substrate and the firstconductive layer; forming a first region including a photocatalyst overthe insulating layer; forming a material containing a fluorocarbon chainover the photocatalyst; irradiating the photocatalyst and the materialcontaining the fluorocarbon chain with light through thelight-transmitting substrate to modify a part of a surface of thematerial containing the fluorocarbon chain which is to be a secondregion; and discharging a composition containing a conductive materialto the second region to form a second conductive layer, wherein thefirst conductive layer does not transmit light.
 5. A method according toclaim 4, wherein titanium oxide is used as the photocatalyst to form thefirst region.
 6. A method according to claim 4, wherein a surface of thematerial containing the fluorocarbon chain is modified so that thesecond region has higher wettability with the composition than the firstregion.
 7. A method according to claim 4, wherein the first conductivelayer is formed as a gate electrode layer and the second conductivelayer is formed as a source electrode layer and a drain electrode layer.8. A method for forming a pattern, comprising the steps of: forming amask over a light-transmitting substrate; forming a first regionincluding a photocatalyst over the light-transmitting substrate and themask; forming a material containing a fluorocarbon chain over thephotocatalyst; irradiating the photocatalyst and the material containingthe fluorocarbon chain with light through the light-transmittingsubstrate to modify a part of a surface of the material containing thefluorocarbon chain which is to be a second region; discharging aconductive composition containing a pattern forming material to thesecond region to form a pattern; and removing a part of the first regionincluding the photocatalyst and a part of the material containing thefluorocarbon chain, wherein the mask does not transmit the light.
 9. Amethod according to claim 8, wherein titanium oxide is used as thephotocatalyst to form the first region.
 10. A method according to claim8, wherein a surface of the material containing the fluorocarbon chainis modified so that the second region has higher wettability with thecomposition than the first region.
 11. A method for manufacturing a thinfilm transistor, comprising the steps of: forming a first conductivelayer over a light-transmitting substrate; forming an insulating layerover the light-transmitting substrate and the first conductive layer;forming a first region including a photocatalyst over the insulatinglayer; forming a material containing a fluorocarbon chain over thephotocatalyst; irradiating the photocatalyst and the material containingthe fluorocarbon chain with light through the light-transmittingsubstrate to modify a part of a surface of the material containing thefluorocarbon chain which is to be a second region; discharging acomposition containing a conductive material to the second region toform a second conductive layer; and removing a part of the first regionincluding the photocatalyst and a part of the material containing thefluorocarbon chain, wherein the first conductive layer does not transmitlight.
 12. A method according to claim 11, wherein titanium oxide isused as the photocatalyst to form the first region.
 13. A methodaccording to claim 11, wherein a surface of the material containing thefluorocarbon chain is modified so that the second region has higherwettability with the composition than the first region.
 14. A methodaccording to claim 11, wherein the first conductive layer is formed as agate electrode layer and the second conductive layer is formed as asource electrode layer and a drain electrode layer.